The automotive enthusiast community has been building their own for decades.

That a good idea in theory, but that has a very high bar for non-advanced users.

What I meant is kind of just a regular brand that offers you a regular car with convenience features, but no telemetry/services involved. All local and offline - that's the catch for them, because what brands want is to monetize services...

The rally fighter and other local motors vehicles are open source iirc, but I agree this should be the future.

Oh, this would be an expensive hobby that I would embrace.

Name's all sorted too:

The Oscar.