Everything involves tradeoffs. The times "we" (previous companies) tried to implement telemetry in open source non-SaaS products (as distinct from "projects"),

Everything involves tradeoffs. The times "we" (previous companies) tried to implement telemetry in open source non-SaaS products (as distinct from "projects"), we either got huge blowback or users/customers simply blocked it at the firewall (and security teams at major enterprises were unwilling to open holes anyway). The only workable solution I found was integrating this in a value-add way, so that something in the service/experience/etc was better for the user/customer as a result of enabling telemetry, without the dark pattern of making things intentionally awful/worse without it. We simply never got enough data to matter otherwise. But, again, that was products and not projects.