I imagine forcing France to give up the Kingdom of Brittany (perhaps to one of George III's younger sons) could have been possible under a much harsher Vienna. Perhaps give Corsica (the birthplace of the Emperor they just defeated) to Sardinia-Piedmont just to humiliate them more. Give French Navarre and Roussilon back to Spain. Possibly provide a port or two to Britain. Give Netherlands some of the historic Spanish Netherlands taken by Louis XIV.
I'm a little doubtful A-L would go directly to Prussia, possibly make it a new duchy for one of those counts and princes of the HRE who lost their throne.
Brittany was a duchy, and had been part of France (de jure and then de facto) for centuries. The notion of carving it off and giving it a British overlord doesn't make that much sense, unless you're really into the "Great Britain/Little Britain" thing. (Even then, the Bretons are descended from people who
fled Britain when the Anglo-Saxons came.) As for getting a port or two, the problem for Britain is then trying to defend it.
I suppose Corsica could be given up, but it was a rebellious island and Genoa was only too happy to sell it to France in the first place.
French Navarre never belonged to Spain. Roussillon could be returned to Spain, but by this point it's been under French rule for a century and a half, so you're talking about not just avenging losses under Napoleon, but under the France of Mazarin.
People are too fixated on the idea of "Alsace-Lorraine" because of OTL. No single territory by that name existed before 1871, and there is no particular reason to believe that Prussia is destined to get it. It's a bit bizarre that Prussia even got the Rhineland IOTL.
There are fundamental problems with an excessively harsh settlement: 1) the coalitions were ostensibly fighting to restore the French monarchy, not undercut it too much and 2) whatever bits of France they take are going to be hard to defend in a renewed war; and 3) everyone was exhausted after over 20 years of war and didn't want to deal with an angry France again.