it is possible to install the new .net core 5.0.5 or 5.0.0 on windows 98, or 2000 and xp in some way even if they have to run each program for one bat.

See:

Net Core 5.0
@echo off
title Run NET Core app on win98 or XP
c:\windows98\programfiles\dotnet.exe c:\user\desktop\netapp\Mynetapp.exe
echo .