Nowadays, you can trade crypto with pretty much any CFD broker. Have you tried?
OK.. they might not offer many cryptocurrencies but still a decent start.
I think brokers added bitcoin against USD on their platform for now. Some of the altcoins added are yet to be active. At least I have seen a pair on ltc with USD but it is yet active for trade.
Is that how the broker manipulates? because I have quite bitter experience with brokers. Since the OP uses a DEX exchange it is clear that his trading history will be quite difficult and will have to record it by copying all transaction data from the exchange address. There is no other way to accept a broker's offer, if it is trustworthy. Meanwhile, our condition is that we are still able to trade freely on the Exchange which is permitted in the country where we live.
The guy is talking about those forex or CFD type of brokers which are typically used under MetaTrader. Generally the way these brokers work, is when you send an order, instead of being routed to the open market, they just take the trade opposite of you. So you are basically trading against the broker instead of open market.
The reason they do this is because something like 99% of all new retail traders lose money, that is what they are betting on, if you make money they will find ways to not pay you.