because of ideological reasons, I also had in mind to flash my device with Ubuntu. However, when I was running Heimdall on my Ubuntu-laptop I got all these error messages on my screen which where not entirely congruent with the image of reality which I had in mind. So then I went to The Duck, spending days (I lost track of time; it could have been weeks) to see if I could find ways to get Heimdall working on my Ubuntu system, because I thought I was doing something wrong. And to my shocking surprise I found this one guy telling on some forum that Heimdall is not meant to be working on a Ubuntu system.
Now I am really not a technician, so I am really not able to tell if this guy is telling the truth, but when I consider that Heimdall & Odin are programs developed by Samsung exclusively for Samsung devices, then it would make a lot of sense to develop these programs to be properly working, at least on a Windows machine.
So then I had to ask myself the question how much I was willing to hold on to my ideology, and how much time I was willing to spent to find out if I was able to make the miracle of the Ubuntu machine happen…
After some consideration I came to the conclusion that I just wanted /e/ on my device, up & running, and if it was really important to me, I always could find out how to get Heimdall working on Ubuntu, afterwards. And when I finally made up my mind, I was happy I still had one desktop in my household, which has W10.
And when I followed the steps explained by @Anonyme, the job was finally done within minutes. After trying all this difficult stuff, this was peanuts.
Now I am running /e/ on my device almost a week! 
I have to admit /e/ isn’t running as smooth as android, but just the thought of being able to bring a mighty organization made up of thousands of clever engineers and smart businessmen on its knees, makes it all up… 
that’s my story how I got in /e/, in short…
good luck
