I would pick Delphi (with which you can build Windows, Linux, macOS, Android, and iOS apps - https://www.embarcadero.com/products/delphi)

Alternatively, RemObjects makes Elements, also a RAD programming environment in which you can code in Oxygene (their Object Pascal), C#, Swift, Java, Go, or Mercury (VB) and target all platforms: .Net, iOS and macOS, Android, WebAssemblyl, Java, Linux, Windows.

I started with VB6 so I'm sometimes nostalgic for it too but let's not kid ourselves.

We might take it for granted but React-like declarative top-down component model (as opposed to imperative UI) was a huge step forward. In particular that there's no difference between initial render or a re-render, and that updating state is enough for everything to propagate down. That's why it went beyond web, and why all modern native UI frameworks have a similar model these days.

I would vote for Delphi/FreePascal, but share the sentiment.

And more performant. Software written for 2005 Windows runs super fast on todays systems.

Only if I don't need to do anything beyond the built-in widgets and effects of Win32. If I need to do anything beyond that then I don't see me being more productive than if I were using a mature, well documented and actively maintained application runtime like the Web.

If it is made to allow C codes to be combined with VB6 codes easily, and a FOSS version of VB6 (and the other components it might use) is made available on ReactOS (and Wine, and it would also run on Windows as well), then it might be better than using web technologies (and is probably better is a lot of ways). (There are still many problems with it, although it would avoid many problems too.)

Or VB.NET? In some ways it's actually easier than VB6

Honestly, it’s probably faster and less resource intensive through emulation than your average Electron app :-/