>I am going to use Certbot to generate my ssl certs. Where does bbbsd find them

Concatenate your key + certificate (with intermediates, if needed) as bbbsd.pem
 and restart bbbsd. That's it.

# cat yoursite-key.pem yoursite-cert.pem > bbbsd.pem

Did you solve libssl.so.1.0.2 vs libssl.so.1.1? You could create that softlink
to bbbsd dir and use LD_LIBRARY_PATH. Something like:

# ln -s /usr/lib/arm-linux-gnueabihf/libssl.so.1.0.2 libssl.so
# LD_LIBRARY_PATH=.:${LD_LIBRARY_PATH} ./bbbsd ...

I'll try to find more time after I return my Toronto / Mountain View / San
Francisco trip. Currently in Toronto...

--- BBBS/Li6 v4.10 Toy-4
 * Origin: * BCG-Box, On The Air Since 11th February 1987! * (2:222/2)