Is there either a US based OR US accessible exchange for Raven and Beam?
There’s plenty of US accessible ones, but not a lot of US based ones. Graviex and Altility still allowed US customers last time I checked, for Raven there’s also Probit and StakeCube. Not sure how much volume they do on each one, but they should let you exchange on there for BTC. Though, I suggest researching exchange fees and withdrawal rates, as they can be a bit high on some exchanges for some currencies.
I mine Raven thru Nicehash and they pay me in BTC
Bittrex is a highly reputable US-based exchange that offers RVN trading pairs. TradeOgre is an option for BEAM with reasonable fees. Regardless of where you go, I always evangelize using referral links so you can bag some initial gains to balance out withdrawal fees. As a little guy, withdrawal fees eviscerate my tiny profits! When I need referral links, I ask friends and acquaintances first and then seek them out in Discord by messaging folks I interact with the most or who have been helpful and previously mentioned using the exchange in question.