How to make Apple Watch Stop SMS/Message Notifications from Unknown Senders?

As another person receiving spam from the Flubot scams, I tried looking into this. There are no easy switches unfortunately, but there are many messy workarounds:

https://discussions.apple.com/thread/250140044

There are other tips that don't work here, such as the option to Filter Unknown Senders, which seems to only work for iMessage, which Flubot doesn't use most of the time. The Silence Unknown Callers option does not work for this case, since Flubot is primarily a text-based scam, not calls.

And also blocking individual numbers, but that doesn't work here either, since Flubot sends from hundreds (thousands?) of different numbers.

There's essentially no real solution for now. You may have also come across this:

https://bgr.com/tech/ios-15-features-sms-spam-filter-brazil-only/

but that is only available on Brazil.