For Monero... I tried the full wallet once (on a server), and it's much more resource intensive than Bitcoin Core, so that's not an option either.
This has been my solution for the last couple of years, and it's actually not that bad. It does seem to take much longer to sync than bitcoin, even though the blockchain size is under 200GB, but once synchronized it doesn't use up much in the way of processing or ram resources.
You make a good point, but it seems excessive for an amount so small that I currently dare keeping it in a closed source mobile wallet.
Maybe there is an option there for private keys instead of key images.
I guess I'll have to create the key image from a private key to use that.