Can I start collecting revenue on my SaaS before registering the company? Also what data privacy clauses should I be aware of?

I am committed full time somewhere but I am this close to launching my own SaaS. It's AI based and hence collects/uses a lot of data to use it.
My question is, do I need to officially register my company and file for taxes or can I NOT file taxes for the first few thousand dollars of revenue.
Also it would be great if I can have some insights on the data privacy clauses I should implement as I don't wanna get tangled in unnecessary legal issues.
Appreciate all the suggestions :)