Stuff I'd love would already exist and I might work on in the future.
ASCII-Art drawing tool for elementary OS AppCenter
It would be great to have an offline capable, ASCII-Art drawing tool available through elementary OS AppCenter. This would allow to create simple graphics in a standardized and long-lasting format - which is especially useful for a Zettelkasten.
There is already a quite good web application called ASCIIFlow which is capable of creating simple ASCII Drawings. It is open source as well, so it would be great to simply re-package it in Flatpak and distribute it through AppCenter for offline usage.
The elementary OS Calendar App currently only features a monthly view for events. While this works Ok, it is not my preferred way for scheduling. I'd prefer a weekly view, since I tend to schedule weeks in advance and block time slots in my days for specific projects. Therefore it is crucial for me to see the available hours per day.
The WeekView is not trivial to implement, since it needs to consider a lot of local factors such as LTR/RTL, timezones, start day of week (Sunday vs. Monday) etc. It also needs to support draggability in order to be actually useful.
But still: It is worth the effort, because I miss this view each and every day.
Installing and using Jupyter Notebook on the Linux Desktop feels a bit clunky: All happens on the command line - although Jupyter itself is GUI oriented. I'd love to have better desktop integration - even just a start menu icon which automatically starts the server and a browser which points at the right URL would be a massive improvement.
The best thing would be to have an pre-packaged Jupyter Notebook app in the elementary AppCenter, which installs everything needed. As GUI we probably can use a Gtk web wrapper, similar to the way Cassidy did it in his Plausibe app for elementary OS. We probably also want to adjust the default Jupyter Notebook GUI, so it provides a more integrated experience on the Desktop. Of course, starting/stopping the desktop GUI should automatically take care of starting/stopping the Jupyter Notebook server.