I think you can use it without enabling telemetry, due to a recent change:

> Previously, access to these changes required you to share technical and interraction data (telemetry) with Mozilla. However, as of Firefox version 148, you can opt into receiving remote improvements, even if you have opted out of sharing your telemetry or participating in our experimental studies.

https://support.mozilla.org/en-US/kb/remote-improvements

> access to these changes required you to share technical and interraction data (telemetry) with Mozilla

How did that even happen? I sure hope that was a bug and not a product decision, because that sounds very backwards.