I bought the game now and i am very excited. I am looking forward to the release but will be there another Open Dev befor the release and is there a date already out? 

Not that I knew, but the game releases in a little more than a month.

I mean I'm somewhat expecting something before release. I been playing Amplitude games since I Endless Legends for me and they always had early access for their games. Now this time they have testing period (which is better in my opinion), but I am expecting that we will see another open dev session. We may not, but the chances might be good.

According to Steam, the release date is 22 Apr 2021, so I believe, at least one more Open Dev is to be expected.

I got the impression when they talked about the game on their 10th anniversary, that they wanted to have another open dev so...

There are 75 days until release.  Assuming they want to make changes/polish the game based on feedback, they will probably need at least a month to 6 weeks to act on feedback, so that would put the next opendev between now and the 23rd of March, if they choose a month (30 calendar days) to work with feedback, or the 11th of March for 6 weeks (42 calendar days.) to work on our feedback.

With all of this said, I have a family wedding coming up March 16th where I will be 500 miles away from my computer.  So, it’s almost a guarantee it will be that week.