If you install fennec from f-droid it’s the same thing as Firefox and provided by Mozilla.

Kernel 5.8 changed this, so the value is from 0 to 200.

https://docs.kernel.org/admin-guide/sysctl/vm.html#swappiness

Glad to hear it worked!

I was dealing with wire guard dns issues recently. What is the interface set to in settings > DNS? I had to set mine to permit all origins for pihole to play nice with wireguard.