Back in the Win98 days, I think a .hta (html application) was meant to be that - like .html but opens as an "application". Never really took off though, I presume due to lack of APIs at the time.

It had access to the full VBScript or JScript runtime and WScript host. This means you could do OLE Automation, filesystem access, network access, registry access, and I believe invoke processes.

At the same time, companies were locking down WScript due to scripting viruses and HTAs that were impersonating other applications with their configrable icons.

This is, or was, sortof that: https://github.com/webview/webview/issues/305