Maybe you can try to make a
PWA (Progressive Web Application), these can run offline in the browser, see:
pwa-framework[
^]
If you already have a website then PWA Builder might be the easiest way to make a PWA, see:
pwa-framework~pwabuilder[
^]
If you want to convert a Windows application take a look at
Cameyo:
desktop-virtualization-solutions[
^]