At Microcenter you can buy a house brand SSD hard drive with 128G on it for $58 and boot from that and store all your other files on a D:\ regular hard drive. That is how I set up my son's Windows 10 gaming rig.
Windows 10 is for newer hardware anyway, it runs slow on older hardware.
In 2018 Microsoft disbanded the Windows team and moved engineering efforts to its cloud and AI teams. Windows 10 is on life support by engineers who aren't intimately familiar with its codebase. Performance and usability will only degrade in this situation and the specifications of newer hardware don't excuse constant deterioration in performance.
Windows 10 is probably slow on HDDs because it's updating a load of UWP apps in the background, resmon.exe disk tab will show what's going on.
I'd rather windows uses my SSD to the fullest, than that it makes concessions to spinning disks.