(I absolutely relate to your experience with sudoku etc. Of course, writing a basic sudoku solver is also interesting.)
The thing is, software architecture and systems design can also get the hobby treatment. I've found that I'm happy to have a short discussion with ChatGPT and have it barf out a few hundred lines of a concept, then refactor and maintain it myself. Or come up with a few different pieces that can be written fairly easily, let the machine skip over most of that tedium, make sure they conform to the interfaces I had in mind, and then verify for myself that the system actually comes together the way I imagined.
Of course, it does help a lot that I can understand the code, and work with it line by line if necessary. But SICP teaches us that it's abstraction and composition all the way down. So I feel like I'm exercising the same skills while not letting myself get intimidated by the sheer amount of initial typing or the self-doubt (instinctive immediate review of the code, you know) that creeps in when I try.