I used to run these for a while, but it gets annoying real fast with large amount of pop-up. So now I stop using them, and only block known bad IPs using my Pi-hole, allowing everything else.
I'd consider this too nit-picky in most contexts, but we're in a thread about connection-blocking software. PiHole is a DNS server. It cannot block IPs or connections.
I'm with you that Little Snitch style filtering gets annoying, but DOH is going to obsolete PiHole / DNS filtering very fast. Can't filter DOH at the gateway without taking on all the other hassles of MITM and can't prevent an app from using whatever DOH server it chooses.
Has the same blocking capabilities, however it is not just install and run like LS is. It needs a little configuring to get it to behave like LS, and (For me) it took a bit till I understood what to turn on and what rules to enable. Once I had the rules setup, it's basically the same. Once an app wants to connect you can let it connect once, until terminated, for forever, to once domain only, or any domain.
FortKnox Personal Firewall works too.
Also, all frontends for builtin Windows Firewall that I've tested, have failed in "2ip Firewall Tester".