This is probably thinking too far outside the box, but how about they sign him to a 2-year minor league deal (they did that with someone a few years back knowing they wouldn't pitch the first year of the contract, right?) with the idea that the first year is going to be rehabbing, obviously, but also essentially in some sort of coaching role? Then, the second year is highly incentive laden so that if he is healthy and is able to return and be effective he's paid what worth. Gets rid of taking up a 40-man space while he's rehabbing, gets rid of the lock-out being an issue with being able to rehab with the team (maybe? I have no idea what the specific rules are for something like that), keeps him in the organization with one more chance to go out as a Brewer on his terms, and maybe gets a useful pitcher in 2028. And if it is clear at some point before then that it just isn't happening and he has the interest, retire and transition into a full time coaching role.
I could be completely wrong, but I can't imagine there are going to be teams are going to be lining up to offer much in terms of a big-league deal given the laundry list of injuries over the past few years.