Pixel 3 user. Everything works great as far as I can tell, the default 1px brush is quite fine which left me wanting to be able to pinch to zoom in to work on the finer details.
For now you can change the Line Thickness in the settings.
Regarding the pinch-to-zoom thing, it has been quite complex and I still haven't gotten it properly so for now I'm creating canvases with a default size (a square with the dimension of the largest screen side). I hope some day I get it working but right now I'm the only person working on the app whenever I have some spare time.
Thanks for your feedback!!