I am following AtomicDex project, there is no website to use, just download wallet for atomic swaps between Bitcoin with bunch of other altcoins, and they are going to add Fiat trading soon.
I've never used AtomicDex because I don't have any interest in the vast majority of altcoins, but it certainly looks like a nice design. Can you provide any links I can read about them adding fiat support though? I quick search of their website, github and subreddit doesn't turn up anything relevant.
As I said Liquid (that is not decentralized) will be used as base protocol and Bitcoin main chain will only be used as alternative option.
It will be used as
a base layer, alongside bitcoin. Bisq has supported other base layers in the past, such as LTC and Doge. You can read the relevant github discussion here:
Bisq already supports multiple/alternative base currencies to Bitcoin for forks of Bitcoin such as Litecoin and Dogecoin. However, since nobody used LTC or DOGE as base trading pairs, they were dropped and Bisq is currently Bitcoin Only. Since the Elements project is a fork of Bitcoin, Bisq could potentially add L-BTC as a base currency.
See also:
the Bitcoin base layer would still be available for Bisq users. Liquid isn’t going to be “the base layer”, Bisq will support multiple base layers and users can choose to keep using Bitcoin blockchain if they want