So I tried out nbrowser but unfortunately saveas is not working for me, as described by someone here: Nbrower node : Saveas doesn't work?
I also tried it with a non-docker installation but also there it is not working.
Would you have an idea on how to use html-to-image? I already worked with the function node and npm modules but always had to get a lot of support as - honstely - I pretty much have no idea how to convert the samples of such nodes to work in Node Red.
Thanks!