Right now, the best way to convert USD to a custom ERC-20 token, like DEV is to first convert the USD to ETH and then convert the ETH to DEV with an exchange like Uniswap. Along the way, the ETH might also be wrapped to be compatible with the token.
Is there a service that is able to convert directly between USD and a custom ERC-20 token contract address or at least do the 2 aforementioned steps automatically?
You need to have somebody to create a liquidity pool for your token and USD pair on Uniswap and then you can directly convert. If nobody provides liquidity to this pair, then there is no market and you need to do a three way trade.
Note that Uniswap can do three-way trades automatically, you just input the token and e.g. USDC in Uniswap and even if a direct pool does not exist, Uniswap will route you a trade through token-ETH and then ETH-USD pools.
