This is all Firefox's implementation of the client. In the dropdown it shows wallets that it sees as available. I was able to test with coinbase wallet, for you it seems like coimbase alltogether is blocked, yes, but also, for example when I install Metamask extenaion - it becomes available as an option, so you can, in theory use whatever crypto wallet is available in your country. But yeah, as the top comment says - the legality of the whol thing is questinable.

> This is all Firefox's implementation of the client.

Nothing to do with Firefox, it’s just the browser rendering the page.