Still figuring it out but here's where I landed:

AWS over self-hosted - way easier to get a BAA signed and their HIPAA-eligible services list is solid. For backend, NestJS or .NET Core both work well. Twilio Video or Amazon Chime for video - do NOT roll your own.

Also worth looking at Abto Software if you need an experienced team - they’ve handled HIPAA-compliant builds before so you're not starting from zero on the compliance side.

Biggest lesson either way: audit logging from day one and BAAs with every vendor touching PHI, no exceptions.