BuyFromEU

"Parent-proof" as in 'they are old and clueless users' (a bit like myself) or as in "I'm a minor and I don't want my parents to get a look into my por... personal library of cute images" ?

Half-trolling here but not completely: if you're a minor, there is very little ways to put any of your data out of reach of your parents.

As for cloud backups. I don't know much alternatives to Backblaze (I used to one of their customers) but I now use European based cloud storages as backups. It works depending the volume of data:

• Filen.io is E2EE and relatively simple to use once configured for yours parent. If you purchase it during the Balckfriday sales you should be able to buy buy lifetime plans instead of the traditional subscription plans plans (that' whats I did, 3 years ago, still going fine).
• If one tera of storage is enough: Infomaniak KSuite+ is very easy to use but not E2EE. It's less than 2€/month including an email account, some other extras like an online version of the office suite. And you can purchase extra storage up to 6To.

They both have mobiles apps, if you need that.

Filen is the less 'user friendly' of the two (nothing that bad either, it's just.. less polished and somewhat clumsier) but the most secure and privacy respecting as far as I can tell. Both are working well once they're configured. I really love Infomaniak's simplicity to be honest. It's also simpler to share stuff with other people.