PSA: Have you heard the good word about Progressive Web Apps?
Like a web app, nothing to install. Lives in your browser tab. Cannot install toolbars or viruses or malware outside the tab.
Like a native app, you own your data. It lives in your browser tab.
Like a native app, can be completely offline. Just host it on a server somewhere as static files, load it in a browser tab. Now you have it cached on your machine, it won't expire.
The only caveat: it _can_ exfiltrate your data in the browser tab. Go forth and share small PWAs with no dependencies that are easy to inspect with eyeballs.
(People who know more, please correct/educate me. I have been utterly oblivious because every PWA I've ever seen has been the lousy kind: some Principal Agent trying to insinuate themselves into your habits, constantly call back to their servers, keep their grubby paws in your data, using a bazillion dependencies to guarantee they lose control of their supply chain and your data. Please also share all the good PWAs I have somehow never encountered.)
@akkartik The biggest caveat: if the app uses browser storage your data may be lost at any time. Browser storage can and will be emptied by your browser as it sees fit.
The only way around this is if the app uses the File System API, which is still not supported in Firefox or Safari.