If you're in the same country as your instance admins, sending money via physical letter might not be the worst option. Though they're probably reluctant to give out anyone's home address if they don't have some kind of association with its own office and/or postbox set up.

e.g. my mail service provider explicitly writes that they accept payment via letter.

https://chuffed.org/project/158294-for-those-who-have-no-one-to-campaign-for-them

Can you explain further?

Even better if the payment method doesn't accelerate environmental collapse.

Is Monero as environmentally destructive as Bitcoin? It’s not something I’ve ever looked into

Yes.

Huh, the more you know.

Monero is patched against ASICs and is designed for CPUs.

It is not the same as Bitcoin.