Sorry if I am just an idiot and cant find how to do it but.
I'd love a Solid Colour layer. (Like in Photoshop fill and adjustment layers)
I resize my canvases quite a lot when sketching and use this type of layer as background to have the whole layer filled without having to paint bucket constantly.
Cheers.
P.S.Cant wait for update I see you guys are working on a lot of stuff like floating colour window and reference view that I'd also love. GOod job yall.