Sure but will other Mastodon instances display them?

Idk the answer but I would consider how changing the character limit may affect federation.

Are you sure you know what you’re setting up? A mesh system? And you really get 5Gbps in your home?

Mesh systems are over priced scams. Run some cables to APs, use PoE if possible. Might be more expensive to get 5Gb but I would ask your ISP about how Internet speeds work cuz I doubt you’re getting 5Gbps unless you’re spending $500+ on internet.