Hi,
I have published a gist which describes step by step the installation of Kurento-Media-Server from scratch on a Raspberry PI 3A+.
I encourage you to follow this gist. It should be possible to go through it within about 5 hours.
I'm publishing it, because I think it is time that KMS lands on ARM and I would love to see it on my Jetson Nano too. Unfortunately this is not yet the case. Even though the gist works 80% there are still some things to solve. Maybe the community contributes, I will continue to work on it. I have put my current status on this in the comments of the gist.
Enjoy and let me know how it works.