I am based in California, US. I will either use Stripe for payments, if sales tax is not a concern at this point. Else, I would like to go via a reseller like Paddle to help with tax collection/deposit etc.
I'm not in California and I know a lot of people on HN are, so I'll refrain from giving further advice. If you don't find your answer, I'm sure an hour of an accountants time could help tremendously.