I want to learn docker/k3s in Truenas Scale

[nanopete]

Where do I start, I want to learn
Docker/k3s so I can use/run my own customized debain/ubuntu images in Truenas Scale, so I can work similarly to what I was able to with iocages in Core.
I feel Truecharts and the GUI of Truenas Scale is a bad entry to this.

I thought I would start here https://docs.docker.com/get-started/
Can I use and learn docker/k3s directly in Truenas Scale cli or is there some subtle differences in the implementation of them that would make that a bad idea / I should know of.
Is there a good docker/k3s guide, specifically for using docker/k3s inside Truenas Scale I should be aware of?

Thank you for your advise!
I hope I can level up and end up being of help instead of requiring help.

 

[mgoulet65]

Watching

 

[nanopete]

So far I received this not very uplifting message from Ornias, in the Truecharts discord server

He did say dockers is outdated and github actions and ghcr was his prefered way to go, I just need to understand that then.
It feels like I should be able to do something in SCALE with containers, (or maybe applications) similar to what I could do with iocage in Core.