As promised, now running my small hobby site on ScaleWay. Runs just fine on my light loads - few hundred page views per day, mostly anonymous visitors.
Perfectly usable for Discourse development and smaller communities. They should also scale up rather nicely, if needed. 50GB SSD is a great feature for the price. Single core performance is slow, which is easily seen in slow ./launcher rebuild times, but the web front-end works OK.
NOTE: discourse-setup defines the number of unicorns at 4, as the 2.99€ VC1S is dual core. Their cores are however Intel Atom / Avotons, which to my knowledge are non-hyper threading. I would stick to 3 unicorns.