I'm sorry, I don't have any specific suggestions for you, but I am wondering: is there no open source app you yourself wish existed because you would need it?

Working on an open source app because some else (and not you) needs it, is not a good way of staying engaged and caring about the solution. Being the user and target of a project yourself is usually a much netter way of caring and proposing something tailored to at least one individual, maybe more.

Of course, if you are looking for a programming exercise, go for it, but then you don't need ideas, you can reimplement something which already exists, perhaps which you like, but in your own way. But if you want to have an impact in the open source, it starts by needing something which you don't really find anywhere and taking matter in your own hands to fix it :) this is not meant to disincentivize you, quite the opposite! I hope you stay attentive to your digital ecosystem to see which holes can be plugged :)

I maintain a private list of ideas I just think of as I go about my day, of things I would like to write/create for myself and while I won't be going through with all of them, I hope to be able to pick up one or several of them whenever I have time. I can through some ideas here, not as a hint that you should do it (I'll probably do them myself regardless), but just to inspire you, maybe:

• I am subscribed to a teachable program which has no app and the program is just static information. I want to pull it all and represent it to me offline, not requiring internet to manage my progress. It is also intended to help me archive what I paid for and not depend on the goodwill of teachables to allow me to continue access the resource.
• an RSS feed manager which uses embeddings to automatically organise the content by topic rather than by source.
• an anki plugin to highlight content in the browser based on words from anki that I have and have not learned, to improve my language learning and reading ability.

I have a few more, but this should give you some hints, I hope! Good luck!