Its generally a good idea, but lets put privacy aside. You could check two different block explorers for your balances, and if they are in agreement theres a very good chance you arent being lied to. ..the privacy issue is tougher because you have to send them your addresses so they can serve you your balances.

Also if you know a bitcoiner who has an electrum server, maybe they woukd let you conndcect to theirs.

And really if you have a computer and maybe an external hard drive you can have bitcoin core running ans use a wallet like sparrow to directly connect to it.