If you are looking for a project implementation idea, I've found automating crypto algorithms pretty fun. To piece that together, is a mixture of websockets, rest api calls, implementing standard financial indicator algorithms, then doing some OO and/or functional programming to bring a larger working system together such as a web application front-end for managing it all.
Another one could be using a maps API, and then adding some value to it. Digital graffiti, chatting, idk. Whatever floats your boat.
As a professional, I'm finding the potential for webassembly applications very juicy right now. Just ported a time tested c library over to wasm, and it is kicking ass on the frontend.