I suspect that that is due the millions(?) of XP units in use in industrial and embedded machinery word-wide. It certainly should be a robust very stable O.S. by now.
Losing the legacy software is the hardest thing (followed closely by hardware such as scanners and printers). I had a couple of software titles I still needed to use and ended up going the virtual machine route.
While I’m basically a road warrior and hence need a laptop for my day to day, I found a good deal on a desktop machine that I could bump the RAM to 16gig (memory is so cheap these days!). I tried Microsoft’s HyperV and then Oracle’s Virtualbox. I stuck with Virtualbox because it could let me do “Hackentosh” - run Apple OS’s on Wintel machines.
I have several virtual machines that let me host those old applications just like the “good old days”.
Windows XP Embedded is different than Windows XP run on a home PC.
Microsoft is not issuing updates for either to the general public. The only Windows XP updates that continue are to those organizations (ie: US Government primarily...) that are paying hefty ongoing maintenance and support costs. The updates Microsoft writes for them will never be released to the public.