I'm going to post this as an answer as I've seen the same type of question come up multiple times, and for each I've basically commented the same thing:
It's pretty much impossible to identify this sort of component unless you either have a BOM of the circuit, schematic, or already know what they are.
If you have some rough idea of the function they perform and it is something more complex than say a discreet transistor, then you may be able to identify them by searching for parts with that functionality on manufacturer websites and comparing marking codes from datasheets. But really this is a shot in the dark.
Having said that, based on your description, the SOT23 package device is almost certainly some sort of TVS device - used for ESD and Transient (EFT) protection on inputs. These are quite common on RS485 devices as per this TI application note. There are components like this specifically for RS485 in the same package like this one. Doesn't have the same marking code, but will like have the same function.
The other package as pointed out by @jp314 in the comments is likely some kind of line filter. As you have found WE has some in a similar package with similar markings, so this is quite clearly what it is. In fact looking at the datasheets from that link, this part has a marking of 500 and looks identical to your picture.
For both of these parts, it could be inferred from the circuit what the parts do. Finding a datasheet for the exact part is the hard bit.
I've dealt with RF for about 10-12 years now, and my best recommendation is to spring for the extra $$ and use the antenna mounted to the top PCB. Putting the radiating element under another layer of copper, silicone, and other materials will attenuate the signal by (very exact answer here) a lot. On the other hand, if you plan on using the Bluetooth interface in very close proximity (less than a meter), it may not matter much. You could always build a prototype of each one and use a spectrum analyzer to measure the performance before putting your design into production. Also, if the whole thing is going to be encased in metal, the BT antenna mounted to the top PCB will probably be severely attenuated as well. You may want to consider a material with better RF transparency for the case. Plastic, maybe?
Best Answer
Most Likely a Multilayer Ceramic Band Pass Filter. For the Antenna Stage. (The Schematic below uses RFBPB 2012 in a 0805 sized package, but any similar Filter would be used.)
Most Likely a Voltage Regulator. The IC uses multiple voltages (3.3V VDD, 1.8V, VBAT [Likely 5v]). Alternatively, it could be an opamp, but you need to trace the pins out to know where it goes. Good luck because it seems like a 4 layer PCB based on pictures on Alibaba.
Based off a schematic for the same OVC3860 Bluetooth Audio IC.