Except for the documentation here and in some other websites, in-depth video tutorials were pretty much missing, just found some and I think they are great, although the JTAGulator ads are very much there, but the rest of the information is very good and it seems the people running the channel appreciate open-source communities and I thought it would be a good idea to share.
[NOTE]
Both videos are using a router to demonstrate.
UART:
JTAG:
For those that want the whole hacking playlist: