This sovereignity thing is mystery to me. In Germany we are ruled in the local aea parliament. They decide on schools, travel, air polution, building, energy supply and on and on and on. Health and the care of the needy and elderly is decided in Berlin by the government and the Health insurance system .
I know you want control of your borders, I used to have to fill in a form on the plane for DD2 - a German citizen, and state reason for travel and show this to NON EU Passports official. DD1 is British so after that, I had to go back through UK Passports carrying DD2 who couldn't pass through because she couldn't walk.
Do you want all that back again?
I think the feeling of loss of sovereignity is that you are tangled up in your own red tape.