...
Would a smallish (1GB RAM, 30GB SSD, 1CPU) Digitalocean droplet suffice - performance wise - as a UNO fullnode + electrum server?
Yes, I believe so. You might also want to create some swap space via a swap file. Setting up an electrum server is quite easy, however getting it to talk to IRC so that the clients can see it may take some troubleshooting (for instance, the python-irc package in debian has some issues), I can assist you there.
Indexing the blockchain right now, lets see how this goes.