I’d have to check my iptables syntax again but I’m not sure you want the FORWARD between the networks unless C has a manual route to get traffic for the 192.168.15.0/24 network back via B. You just want to NAT A behind B’s IP on 192.168.38.0/24. I think the forwards are sending the traffic without doing NAT on A.

Right now - easy, with the difficulty going up over time as the main Chromium codebase continues to change (and especially as it gets security updates). I think I’ve read that some variants (Brave?) have committed to supporting ManifestV2 for as long as possible, for instance with their own fork.