I don't have any insights into barca's books, so I can't answer. That's why I wrote "Let's see".
Also you might find this shocking, but he doesn't need to play for free because no player does. He just needs to lower his demands to a healthy figure if he really wants to return. There are also some possibilities to ease the ffp. Find sponsors personally for Messi or give him a longer contract with a low base salary, which turns into an ambassador contract after 2 years so he continues to get payed after his career when barca is financially speaking in better health.
That's now the job of Laporta and Alemany to figure out how much Messi is willing to reduce his demands to return and what barca can offer. We fans have to wait and see.
The idea of Messi feeding Lewy is not a bad one.
It could be something like this:
-----------Lewy
Gavi - Messi - Dembele
-----Pedri - Frenkie