You can add custom code on weweb. For example I have integrated stripe elements.
Some consideration about supabase ui library:
- it is still in development and not recommended for production use
- it uses react, currently react support is in beta in weweb
- you need to pass the supabase client to the auth components. Not sure if the weweb supabase auth plugin exposes the client, probably you need to use the supabase sdk directly in your custom code without relying to the weweb plugin
- weweb is already something like this library: you have elements, builtin ui kits, plugin for auth. Usually custom code is required for a specific functionality, a general library of component is redundant.