You can use another forum feature: Watch board/ Unwatch board.
It's not the same like Ignore board preferences but can give some useful practice and the description says about its utility.
That won't solve OP's concern, his main concern is, he doesn't want to see those child boards on this board. Adding those boards on his ignored list will eventually hide those child boards when visiting this board.
This is the best solution for what the OP wants at the moment, although the "inactivity" of such child boards never bothered me.
The idea of new sub-boards (or whatever this is called) for new wallets like Sparrow and Bluewallet is tempting. I think it's time to consider a renovation of the Child Boards.
I suggest creating something like:
Legacy wallets (not necessarily old, but ones that have been on the market for quite some time and are currently active or not)
> Bitcoin wallet for Android (Schildbatch wallet), Armory, etc.
BIP32/BIP39 wallets (with support for Segwit and other addr scripts type)
> Bluewallet, Mycelium, Sparrow, Wasabi, etc.
Multicoin wallets:
> Cake wallet, Coinomi, Stack, Unstoppable etc.
Armory is a wallet I would love to see back in active development again, completely revamped and with support for the features that the main wallets use today.