So do you want to achieve proof of burn committed to nostr keys? That is easy. To be a proof of burn it would have to be done by deliberately no using a full key pair but only a valid public key with no known private key. Send to "1BURN".

would have to be from the npub you want to commit to but only the first n bytes.

would be the smallest number of bytes to turn the rest into a valid Bitcoin address.

And yes, you will get much hate for this as these would be unspendable UTXOs like inscriptions. With the "1BURN" prefix you would at least tell the world it won't be needed for spends later.