@neil I did lots of research into this and settled on Akaunting, but it's not free if you need advanced features. Self hostable. Very nice GUI and easy to use. Extra users, double entry, and bank sync is extra as "apps". Comes with BSL licence.
I think it's worth the money, but YMMV.
https://akaunting.com/license
https://akaunting.com/plans-on-premise
@neil they also have a cloud option, but in my bit of "due diligence" I couldn't find any compliance docs on security they have, so I wouldn't go there other than for trialing the features to see if they fit your needs.