Just curious why don't you just get another Trezor One? It fit's the requirements of open source and it's in the price range. It also happens to be a great wallet. The only drawback I find is it's not compatible with Monero's official wallet.
Well the thing here is that trezor in general and moreover trezor one does not support coins, which I would like to store.. otherwise, a good wallet. No issues in storing eth and btc.