Contributing to FOSS isn't a job that you apply for and get approved to work on. Nobody cares what your credentials are. Every pull request you make stands on its own. Your pull request is your "job" application -- Proof of work comes first.

The other contributors that work alongside you are not your co-workers. Nobody is paying them to read your messages, mentor you, or even to give feedback on your pull-requests. You have to become the champion of the features you want to see and be ready to abandon your previous efforts for no reward if the community/maintainers disagree with you.

The best FOSS projects start by a developer scratching their own itch. There's no shame in building something for only yourself in silence. Many devs lack the fortitude and grit to build in silence, so you may find it better to build in public if the social pressure helps to keep you accountable towards your goals.

Occasionally, what you build might be useful to others, if you open source it, others might find it so useful that they'll begin to grow and maintain the project for you.

Not ready to start from scratch? Start with the FOSS tools you already use. Check out their tech stack on github. Try to run the project locally. Having issues running it locally? Make an issue! Found an easier way? Contribute to the documentation, or build tooling.

If you explore enough, you may find a FOSS project with grant funding and a "work-culture" or bounty program that feels familiar to you. It's just not the default mode in FOSS. That said, most FOSS has just one maintainer and they'll usually welcome help and feedback any way you can offer it, they're just too busy to be your boss or manager so expect to be self-led for the most part.