Create profiles and assign them time with more than one device?

I want to limit my kids' internet time across all their devices each day. For example, I'd like to allocate 60 minutes from Monday to Thursday and 120 minutes on Friday, Saturday, and Sunday. This time limit is for each child and covers all their devices (phone and tablet), not each device separately.

To achieve this, I was thinking on creating separate profiles for my daughter and son on the router, assign their respective devices to these profiles, and set daily time limits (e.g., X minutes on Mondays, Y minutes on Tuesdays, etc.).

The key point is that the allocated time for each day is shared across all devices. For instance, if my son has 60 minutes today, he can use any combination of his devices, such as 30 minutes on his phone and 30 minutes on his tablet, or 45 minutes on his phone and 15 minutes on his tablet. He doesn't get 60 minutes per device; he gets 60 minutes total for all devices. Once the limit is reached, internet access is blocked on all his devices.

Additionally, I should be able to unblock or adjust the daily time limit as needed.

Is this possible to do with OpenWRT? How? Thanks.

You have google and apple parental controls. Open!rt does not have ways to break into airplane mode and other baby level hacks.