You might be able to do mac address cloning for fiber ports, if you have openwrt or similar it usually offers it.
A firewall may not offer full routing and NAT though for ipv4 devices, or wifi if you need it, or ipv6, or many other features. I’ve also used a cable modem and stuck the router in the dmz which essentially makes it a passthrough device also in the past
Basically, play with it and good luck!
So as much as I dislike crypto, it is basically built to be enshitification proof. And hence a good fit for the fediverse. But I wouldn’t want to touch the crypto ecosystem with a ten foot pole, nevermind a lemmy/mastodon integration
Which leaves us at the behest of traditional payment processors, and they are all faceless conglomerates who care not for anyone. Meaning we’re fucked there too
Maybe we should instead not bring transactions to the fediverse