Since i had any kind of smart-phone, i was always frustrated, when i joined to a network on a phone -maybe weeks since the last connection, because i was ok with a PC- and everithing statrs blasting any sync, or update-request data.

I know GOS, is way more limited ( & limitable, trimmable), but similar situations still can happen. ( E.g. "
I want quickly check this site, on my network's wifi, now in less than 20 second>> full sysupdate-check, and possibly update starts" - sure, my network trustable, even unlimited, and i usually want an updated phone, but for that 10-20 sec, i would like to check that site only.
My goal would be:
If i join to a network (know or unknown), let me -on the spot- decide, if it safe, or not, AND what app can communicate on that, in THAT SESSION. Or select a "network usage category" for that session only.

Is there an app, what could manage this situation safely?

Also, i have OpenWRT and on that a Pi-hole like dns based blocker, not for just ads, and i have portmaster for PC, and Ublock origin for browsers. I know some is redundat, but i like them all, because i have 3 level of monitoring with them. Also 2 keeps time-limited logs, so i can check what happened, what was blocked, etc.
But what can i do with mobile, if i would like to see my incoming outgoing requests, directions (per app maybe)? E.g. One banking app worked flawlessly to buy a thing online, but the phone got hot, so i checked, and my router blocked a google servece, wich was blasted by the app in every 2 seconds for 10-15 mins, and i lost 20% of battery. Do i need that service? I was fine without it... Less drain on battery if i block it before the wifi modue? IDK... Am i want to enable it? Not really. If i am on the go, how can i block it?
Sure "use a good vpn", but i would like to be able to see what is blocked, and if i do not want a connection, is that blocked?

Any solution for the 2nd problem? The ability to monitor would be a priority, blocking is a secondary.
On-device Recursive DNS?

(After writing, before posting i have checked all results to DNS here, on the forum, and that made me sad :) )