Ask experts? ($99/yearly sub)They are selling their knowledge for money... You can get all the information you need here for free. Some bitcoin devs are still reading this forum and even if you can't reach any devs, there are other people as informed as them will answer your questions for free just to help bitcoin adoption.
Don't forget Bitcoin Stack Exchange. Absolute gold mine that. A few days ago I asked a question about default private key types and I got an answer from Pieter Wuille the next day.
Beside this place there is also r/bitcoin (becoming a bit spammy though) and Stacker News, although I guess these are not so oriented to "Expert Questions". And then there is the bitcoin-dev mailing list itself, which is.
Certainly stackoverflow and its subforums is one of the best forums in the internet.
I also like reddit. There are a tons of good places to share knowledge in the internet. As elon musk said, you can learn basically anything for free in the internet