I don't know about that. I suspect, generally speaking, per-user billing does not work for the vast majority of SaaS. It can really only work well in communication tools, where (1) most organizations receive a lot of value, (2) there's a network effect in play, and (3) expenses incurred by the provider generally correlate with the number of users. Slack. Jira. Notion. Etc.
For an APM tool like Apollo, only one of these requirements is true. It does provide a lot of value. But, there's no network effect, and their expenses do not correlate with users on the platform. That last point is the craziest one; being long-time users of Meteor and Apollo, I've always questioned the technical and executive leadership behind the Meteor Development Group (now Apollo), and they've done nothing in recent history to give faith that its a well-ran organization.
Retool (https://retool.com/) is another weird one. Amazing, amazing product. Truly transformative; what they're building there is unreal. There's a very light network effect in play, and usage may correlate better with users-in-app than it would with Apollo Engine, but charging per-user still feels weird. For them, I feel some form of bucket'ed plans, which allot X users, Y "applications", plus gated feature sets like SAML and Audit Logging, would make more sense. But, what do I know.