this is not supported in the new UI due to an unfortunate design decision about how the content tree relates to the node-entry relations. So we first need to fix that, then we can enable sorting (e.g. by dnd in the lists) in the new UI. Fixing it has been on the backlog for a long time but unfortunately there is no obvious solution and also any solution would introduce breaking changes.
I feel lika an idiot but how do I change the sort order of nodes and products in the new Commerce GUI?
In Commerce Manager each node and entry has the Sort order property but I can't find that in the new GUI and neither can I drag and drop products.
What am I missing? :)