Hi@kb42,
@kb42 wrote:
Can you not edit Powerapps forms in Teams?
Are you sure that you want to not edit the PowerApps form in Teams?
However you want to edit the PowerApps form in Teams as you described at beginning.

If you expect the form to be editable in Teams, could you please check the first solution I replied before?
Besides, if you want to pop up a new form when you click a item within the form in Teams app, I don't think the current function PowerApps provided in Teams could achieve your needs.
Let me make it easy for you, the PowerApps form in Teams is designed by default, it could not pop up a new form when you want to edit a certain item. Select the item you want to edit from the Gallery and click the pencil edit icon to make the form editable, then you can edit in the PowerApps form where will never pop up a new form as it does in the SP list.
Hope I explain it clearly this time.
Best Regards,
Qi