This is the best way to do chanelpoint sounds imo. Love it so much and has no glitches (I've had some alerts not go through sometimes) and is all run from your own machine, not from the web.
I would love it if this could also be used for Follows, Raids, Subs etc, So I can have everything managed through this, and so follows can't overlap chanelpoints.
> custom size for each reward individually
If you're talking about a VLC source with several random videos, then right-click the VLC source, click "Transform", then "Edit Transform", and choose "Fit" or "Fill Width/Height". This way high-resolution videos will be resized to the source's bounding box.
For Media Sources, you can resize them like usual via OBS by dragging the bounding box by its corner.