As far as I know, browsers do not have any .eth nor .btc TLD support, so you use some web bridge service, like eth.link.

So the website hosted for vitalik.eth is accessible by any browser (as it uses simply DNS) at vitalik.eth.link

https://vitalik.eth.link

I don't know if a bridge for .btc TLD is already online, or what. (nor do I necessarily plan to use one -- that adds an unnecessary layer that probably is not secure and certainly won't perform as well as a connection that doesn't go through this bridge).