24 hours ago, I finally bit the bullet and dug up my old computer, set it up physically, installed Linux Mint (with full disk encryption), installed Bitcoin Core through its software manager, started it, immediately selected "pruned mode" in the settings (kept it at default 2 GB since I have no idea if it's good or bad to increase/decrease it), closed it and started it again, to let it sync from scratch to 100%...
When I went to bed, it seemed awfully unresponsive, with mouse movements taking several seconds before they showed up on the screen.
When I woke up just now and looked at the progress, it was still at 21%, with "10 weeks left". It now would not at all react to any attempts to close it or click on anything. I had to "hard-cut" the power to the machine and restart it. Now I'm again running Bitcoin Core and so far, it seems very responsive and says "10 days".
It's connected directly to 100/100 Mb/s fiber, and the hardware is 3 GB RAM and a 2011-era Dell CPU. Dual core something. The HDD is 250 GB and mechanical. (Which is why it was not a choice to store the entire blockchain and I had to use pruned mode right away.)
I don't know what to make of this. My guess is that it was not actually doing any work during the entire night, instead having somehow "hung". I sure hope it's not some hardware issue or something, because that machine is the only practical means for me to have a decent chance of setting up a secure new wallet for cold storage.
Others online seem to be talking about "hours" to sync, but this seems like it at best will take at least four days, if everything goes perfectly and progresses exactly like it has so far, minus the hanging. And again, the program itself is talking about "10 days"... nope. Now it says "6 days". I just looked over at the screen.
Basically, I have no idea what's going on.