I have found very few programs which work in Win7 but fail under Win10. The problems seem to be in device drivers, because Win10 has extra demands for the likes of low power modes. Chip makers don't like updating drivers for old hardware; they would rather sell new chips.
You will be running a 32-bit version of Win7, which would be updated to the equivalent 32-bin Win10.
Your old 16-bit software won't run under any 64-bit Windows (including the 64-bit XP). Microsoft allowed only a single "step down", because things get too complicated internally, especially dealing with software security. "Won't work in Windows 10" probably means "Won't work in Windows 10 64-bit" because modern machines almost certainly arrive with the 64-bit version installed.
Win11 does not have the option of a 32-bit version; it will run 32-bit software, but never 16-bit.
That said, I do have one machine where Win7 is the newest possible version, because its processor does not have certain instructions needed by newer versions.