missing-root oh boy, here we go:
Dont host Nextcloud, that is not easy
That's nonsense. We don't live in 2010 anymore where you need to sit for 2 hours in /etc and /var/www and download 30 php modules, we have nice All-in-One solutions via docker.
Maybe it is if you are in the USA where everyone just has a static IP.
You don't need a static IP. I run my stuff on a dynamic residential IP without any issues. Sure, when it changes it takes like 10 minutes for the TTLs to run out, but I can live with that downtime. Setting up a duckdns script takes literally 20 seconds.
Just get a phone with enough storage. What does she need a cloud for?
Redundancy? Backups? Shareability? Centralized photo management? There's more than enough reasons.
The rest is debatable, depends on the user, needs and threat model. I personally would still recommend Private space over work profile (although I use both for different purposes).