You could do a wallet instead of only a portfolio as a programming project. You would for sure need some in depth knowledge of how bitcoin, eth and other crypto currencies work as your wallet needs to know how to construct them and how much fee needs to be included. If you do plan to go with that I would advise to read a book by Andreas called “Mastering Bitcoin”. The book goes in depth about how bitcoin and transactions work.
Maybe even a better option would be some kind of an application on the ETH network. Maybe even just contributing in some of the ETH DeFi projects would be a great start. I am sure there can be build some programs that just could not exists in a centralized manner. Smart contract programming and defi project are getting more and more attention.
Maybe help with the bitcoin lightning network if bitcoin is more your thing.