I have an angle stand that does well for a variety of large and small
brushes. Finding one that stands vertical is harder than I expected.
I just looked for the one I have and it seems to be hard to find....

Stainless welding rod is easy to find... So is PVC pipe.
Cobble together something practical, yes even bent coat hanger.
You do not want your new brush to get old before its time
by letting water pool in the knot.