Yah, pretty expensive. There are two modes to run ord in, one which indexes the sats in every UTXO, and one which doesn't. Everything works in the latter mode, you just can't see specific sat numbers. (But inscriptions work, since that's not dependent on sat numbers, just sat movement.) Building the full index requires ~150 GB of space and 64 GB of ram to do in a reasonable amount of time.

I love the idea of Ordinals as Nostr identifiers, but having to run a bitcoin core node and ord index just to be on Nostr sounds like a hard sell!