It looks like you’re missing the ydotool.service unit file in the package. Can you check by running dpkg -L ydotool-custom (the name of the package you chose in step 3.4)?
Unit files are how services are defined in most Linux-based desktop systems, similar to services in Windows.
This may be true, however a simpler explanation is that a lot of people are in relationships, so the prior probability of liking someone who’s not in a relationship is already low. Also it could be that attractive people are more likely to be in a relationship, further reducing this probability.
I used to be a dual monitor user, but nowadays I'm using a single large monitor because I had to rearrange some things in my work room. For work a single monitor is fine, but I'm also doing some Twitch streaming, and multiplayer gaming, and for that I actually am now thinking of going back to two monitors.
The other important thing for me personally is resolution. If I'm working with text, 4k is absolutely necessary, for gaming UHD is fine.
Monitor arms do help with desk space a lot. However, you should also keep in mind that you will need some clearance behind the deck for the "elbow" of the arm.
The other option to save space is a shelf stand, which raises your monitor a little above the table and allows you to store something under it.
What features do you need? Just render a string with a given font and that’s it? Or something more advanced?