Night Vision what to do with a Omni VII gen3 tube

It's not as simple as just swapping the tube in another unit, clip ons aren't like PVS-14's. Whatever unit you put it in has to use that specific tube and I'm not aware of any clip ons that use the same tubes as PVS-14's though I could be mistaken.

You'd be better off selling the functioning PVS-14 and putting it towards a clip on purchase.