I can't really comment about fake braces with brackets etc but I have Hawley retainers and also simple plastic bite plate without front wires.
I wore one or other, full time for about 4-5 years, only taking them out to clean them or swap from one to the other. I didn't eat anything without a plate for all of that time! (I only started to go without them after I had a tooth extracted and started to get trapped in the gap but I still wear them often). Sometimes I wear the activator in my avatar photo, but not so much, and it is impossible to eat anything with that, only drink.
The Hawleys stand up well to eating most softer things and the bite plate is fine for eating anything apart from chewing gum!
In fact I got used to eating with the roof of my mouth completely covered and it was uncomfortable to eat without that.
I somehow enjoyed the feeling the first time that I finished a meal and had forgotten that i was eating with a retainer in.
