I'm only really interested in the former. Hadn't considered charging *per* read or impression. Seems hard to measure given what you've said.
Discussion
I mention it mostly because the ‘impression’ metric is largely related to todays advertising business models.
At some point someone is going to want to try tracking impressions or a derivative and charging - ideally it’s unworkable and fails. Advertising is a burden on society.
And certainly Nostr will always be read biased. More likely 100-10000x as it grows.