I had a repair for GPEH, and nausea is not a normal reaction. It can be caused though, by pain meds or food intolerances.
My GI has me take Nexium when I am having a bunch of nausea problems - because mine has reherniated partly into my chest. But mostly I just have to not eat anything to which I am sensitive. That includes drinks and meds.
If you keep a good food journal with everything you eat or drink and meds, plus the times and any reactions you can eliminate most foods and find out if you have any food triggers. It can take a couple of months, but it's worth the try. My allergist got me doing this and I've kept it up for years.
As far as exercise, you are only a little way out of major surgery and shouldn't push it yet! It takes at least 3 months to recover from something as rough as you had. Walking is fine, but no weight lifting, twisting, anything hard. Few others on the forum have had as much done as you. You need much longer to recover than someone who has had only a simple wrap.