Isn't it pretty easy to set up a whitelist of apps/websites kids are allowed to use?
Whether or not that's a healthy thing for your parent/child relationship is a different question.
It's simpler to take the phone away. And iPad. And stop hanging out with your friends that have it.
Phone management is hard to solve for pre-teen and teens.
It's like taking heroin away from an addict. They hate you for helping.
OP already gave you your answer, you just chose to ignore it
They are both very bad at things like my kids listening to Spotify with the screen off.
Qustodio also has no way to mark an app as "allowed even when they run out of time", or "this app doesn't count towards screen time" (like Spotify, for example).
Then on the PC it gets MUCH worse. I want tracking and blocking on my PCs for my kids' profiles, but if ONE kid runs out of time, ALL the PCs lock everyone out. No message, either. Just bounced to the login screen. Took me like a whole day to figure it out.