Mostly I have been working on a software project called TeXnicard, which is not yet complete, but a lot of things have been done, as can be seen from the timeline view of the Fossil repository. In doing so, I have found a bug (#702472) in Ghostscript, having to do with the printobject and writeobject operators. I both reported and fixed this bug, but have received no reply from Artifex about it so far. (The patch is currently included in the TeXnicard source repository, in the file called "gspatch.txt".) I have done some other things too, such as some improvements to ZZT (such as listing the date/time in the restore game menu), but the thing I have been working on most is TeXnicard. I have not done any hardware projects, though.
Some of the other ideas listed here look like interesting ideas too, although I don't always like the implementation. (I suppose that isn't so uncommon; that is why there are many different programs and other projects for similar purposes.)
But, occasionally I have played GURPS using the internet. Before the lockdown I was not doing it on the computer, but now I am sometimes doing. Since I am the only player, I simply used a direct connection; I wrote a shell script containing a command like this one:
ts '%.s>' | tee -a send.log | nc -Clvt 12345 | ts '%.s
We then coordinated the times with email, and he sent a bell to my terminal when he was ready. And then, I can just use "cat" and "sort" commands to produce a full log.