> Servo was never meant to be a full engine replacement for mainline Firefox
I don't think that's a fair summary of the history. There were multiple points of view on this inside Mozilla, and some (including myself) definitely hoped it would be a full engine replacement.
However, regarding Servo specifically, there are contributions on their GitHub[1] and the stewardship of the project is now under the Linux Foundation[2].
[1] https://github.com/servo/servo/commits/master [2] https://blog.servo.org/2020/11/17/servo-home/