I've imported my Unstoppable wallet seed in Electrum-LTC. Note: there's a risk in doing this, so don't do it unless you know what you're getting into. For me, this was okay, as I only have a small amount of LTC and no other coins in Unstoppable.
Electrum-LTC shows what I think is the correct balance.

I'm disappointed in Unstoppable: this meant I couldn't make a (small) transaction yesterday when I wasn't at home, which is the only reason I have this wallet. Obviously I didn't bring my seed phrase with me, so I couldn't recover it. And Unstoppable itself allows me to create a backup, but not to export the seed or private keys.
Meanwhile, Unstoppable's server is still stuck somewhere in February.