Screentime controlled from smartphone - firewall rules

I have one simple firewall rule to block the Internet (simple screentime for my son).
The rule is assigned to a MAC address and works from 22:30 to 07:00, so that he cannot play games, watch YouTube videos, go to Facebook etc during the night.
Now if I want to change the firewall rule hours or enable/disable the rule, I have to log in to Turris Lucy interface – it’s not practical and it’s time consuming.
I would like to control the rule from my smartphone.
Technically, I could run a cron job, to read a file from OneDrive for Business, the file would define the screentime hours and enable/disable flag. I could create an MS Power App to control the file on OneDrive for Business (I have Microsoft 365 business subscription).
What would you suggest? Any better idea? I am not so much in favor of creating an app, that would directly access the router…, SSH, web access, etc.
Many thanks!