Nginx – Automatically choose SSL Certificate based on accessed hostname in the same vhost

I'm using nginx to serve my Nextcloud instance over a local connection with SSL (in this case the domain is called nextclowd.raspi.local and it is using a self signed certificate).
Now I want to make it accessible through a DDNS domain, which I want to encrypt with SSL too (I already generated a Let's Encrypt certificate for that domain).
But now I'm having problems with getting it to work with both certificates. I could use the DDNS certificate for my local connections too, but that always throws me warnings, because the certificate does not match the domain.
I also want to avoid defining two vhost entries (because of configuration redundancy). I also read things about SNI, but from what I have been able to understand is that not the thing I want.

Is it possible to make nginx choose the correct SSL certificate based on the domain that was accessed while being on the same vhost?

Here is my current vhost file for reference:

server {
    listen 80;
    server_name nextclowd.raspi.local mydomain.ddns.net;
    # enforce https
    return 301 https://$server_name$request_uri;
}

server {
    listen 443 ssl;
    server_name nextclowd.raspi.local mydomain.ddns.net;

    # My self-signed SSL certificate
    #ssl_certificate /etc/nginx/ssl/server.crt; 
    #ssl_certificate_key /etc/nginx/ssl/server.key;

    # My Let's Encrypt SSL certificate
    ssl_certificate /etc/letsencrypt/live/mydomain.ddns.net/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/mydomain.ddns.net/privkey.pem;

    # Add headers to serve security related headers
    # Before enabling Strict-Transport-Security headers please read into this
    # topic first.
    # add_header Strict-Transport-Security "max-age=15768000;
    # includeSubDomains; preload;";
    #
    # WARNING: Only add the preload option once you read about
    # the consequences in https://hstspreload.org/. This option
    # will add the domain to a hardcoded list that is shipped
    # in all major browsers and getting removed from this list
    # could take several months.
    add_header X-Content-Type-Options nosniff;
    #add_header X-Frame-Options "SAMEORIGIN";
    add_header X-XSS-Protection "1; mode=block";
    add_header X-Robots-Tag none;
    add_header X-Download-Options noopen;
    add_header X-Permitted-Cross-Domain-Policies none;

    # Path to the root of your installation
    root /var/www/nextcloud/;

    location = /robots.txt {
         allow all;
         log_not_found off;
         access_log off;
    }

    # The following 2 rules are only needed for the user_webfinger app.
    # Uncomment it if you're planning to use this app.
    #rewrite ^/.well-known/host-meta /public.php?service=host-meta last;
    #rewrite ^/.well-known/host-meta.json /public.php?service=host-meta-json
    # last;

    location = /.well-known/carddav {
      return 301 $scheme://$host/remote.php/dav;
    }
    location = /.well-known/caldav {
      return 301 $scheme://$host/remote.php/dav;
    }

    # set max upload size
    client_max_body_size 512M;
    fastcgi_buffers 64 4K;

    # Disable gzip to avoid the removal of the ETag header
    gzip off;

    # Uncomment if your server is build with the ngx_pagespeed module
    # This module is currently not supported.
    #pagespeed off;

    location / {
        rewrite ^ /index.php$uri;
    }

    location ~ ^/(?:build|tests|config|lib|3rdparty|templates|data)/ {
        deny all;
    }
    location ~ ^/(?:\.|autotest|occ|issue|indie|db_|console) {
        deny all;
    }

    location ~ ^/(?:index|remote|public|cron|core/ajax/update|status|ocs/v[12]|updater/.+|ocs-provider/.+|core/templates/40[34])\.php(?:$|/) {
        fastcgi_split_path_info ^(.+\.php)(/.*)$;
        include fastcgi_params;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        fastcgi_param PATH_INFO $fastcgi_path_info;
        fastcgi_param HTTPS on;
        #Avoid sending the security headers twice
        fastcgi_param modHeadersAvailable true;
        fastcgi_param front_controller_active true;
        fastcgi_pass unix:/run/php/php7.0-fpm.sock;
        fastcgi_intercept_errors on;
        fastcgi_request_buffering off;
    }

    location ~ ^/(?:updater|ocs-provider)(?:$|/) {
        try_files $uri/ =404;
        index index.php;
    }

    # Adding the cache control header for js and css files
    # Make sure it is BELOW the PHP block
    location ~* \.(?:css|js|woff|svg|gif)$ {
        try_files $uri /index.php$uri$is_args$args;
        add_header Cache-Control "public, max-age=7200";
        # Add headers to serve security related headers (It is intended to
        # have those duplicated to the ones above)
        # Before enabling Strict-Transport-Security headers please read into
        # this topic first.
        # add_header Strict-Transport-Security "max-age=15768000;
        #  includeSubDomains; preload;";
        #
        # WARNING: Only add the preload option once you read about
        # the consequences in https://hstspreload.org/. This option
        # will add the domain to a hardcoded list that is shipped
        # in all major browsers and getting removed from this list
        # could take several months.
        add_header X-Content-Type-Options nosniff;
        add_header X-Frame-Options "SAMEORIGIN";
        add_header X-XSS-Protection "1; mode=block";
        add_header X-Robots-Tag none;
        add_header X-Download-Options noopen;
        add_header X-Permitted-Cross-Domain-Policies none;
        # Optional: Don't log access to assets
        access_log off;
    }

    location ~* \.(?:png|html|ttf|ico|jpg|jpeg)$ {
        try_files $uri /index.php$uri$is_args$args;
        # Optional: Don't log access to other assets
        access_log off;
    }
}