I like notion a lot, especially for its databases function, it's much more powerful than stuff like excel, but being proprietary I'm scared of the buyers lock in / notion disallowing exports in the future and all the cons that come from using a proprietary software. Also managing integrations is probably harder than with an app that you own I think..

Is database in notion just a normal database like mysql? How easy/intuitive would be making the switch? Is it worth it?

We would use it for a very small organization, mostly for registering invoices, documents, lists of contacts with several informations.

I need to query results and to sort / filter database as I want, there's also the idea of trying integrating it with a website in the future maybe..

I like how practical notion is, but I don't like that it's proprietary and notion could potentially modify its terms of use whenever it wants.