i don't think exactly what i'm using is 'older' as they're still supported :P
but i use Audacious, Audacity, XFCE (my DE), my main laptop is a HP Elitebook from 2013; i'm playing older Minecraft, etc.
at least some of those are still supported, anyways. old Minecraft is nearly entirely forgotten outside of Minecraft Classic, though.
i've especially noticed i've wanted to use older Vocaloid-ish programs, like VOCALOID Editor 2 or 3, UTAU, MikuMikuDance 2.X, etc - i think mostly because they kinda carry a weird charm with them, plus they're seriously lightweight
and my 3DS as well, though i still use my Switch (i'm actually using it more than i ever have ever since i played Pokemon Violet on my Lite a year or two ago now) especially with Pokemon X and probably gonna play Moon using my old cart for it. though it's homebrewed, so i'd rather have Ultra Moon lol, though my SD card is completely full already (it's only 8GB but still)
plus similar with older games actually.
been wanting to play Touhou for soooo long but my own hardware doesn't even seem to like it one bit; though Kirby Air Ride is really fun, so is Kirby Squeak Squad, Pokemon Platinum, Project DIVA 2nd (and Extend), and really Alien Hominid too.
i wouldn't go so far to using something like Windows 98 or an iMac G3 to run this site and only this site, no way. but i like the idea of getting older hardware and running modern Linux onto them