Have you considered Godot? I don't have any real experience with it, but from what I gather, it's FOSS, seems pretty popular and well supported, definitely supports 2D (also 3D but you don't care), can export to Android or web, as well as PC, and doesn't use any of your "blacklisted" languages. It uses its own python-like script, or you can use C#, and there's extensions for others.

Godot is great for 2D, is FOSS, and it is getting stronger by the minute. Where it doesn't meet your requirements is perhaps that its main language is their own GDScript. it's a really easy language to get started with, but still "obscure". You can, however, use C# to do (I think) anything you could with gdscript.

You can also use C++ to do everything. This is called GDNative. With this you're basically just rewriting / adding to the game engine that is written in C++. Probably harder to get into, especially if you're not too familiar with the language.

I had experience with python so GDScript came naturally, and the documentation is really thorough.

With Godot you can export to Windows/Linux/Web in one click. Exporting to Android just needs like 15 minutes of setting up using the tutorial in the docs, and that becomes single click too.

You can even download the game engine onto your phone and it works the exact same there! Though I wouldn't want to develop on a tiny touch screen lol

I'm not sure it fully meets the specs, but have a look at the TIC80 it's an open source fantasy console you can write code for.

Imagine something like a 1st generation console game system fully sypported by emulators. I've touched on it on a recalbox.

Rust is newish but it's not going anywhere anytime soon. If you've got the chops to work directly in code without a built-in editor, try Bevy. Seriously. It's the future of game dev.