Migrating Git repositories to Mesh before migration of LFS objects is implemented is very much possible and supported. The LFS object will continue to reside on the NFS based shared home and can be migrated later.
Generally lack of LFS migration doesn't need to be seen as a blocker to adopting Mesh. Core Git I/O patterns often involve small and semi-random I/O, which suffers due the additional latency involved in accessing files via NFS, this isn't so true of LFS objects. Git LFS object read I/O is involves large block and sequential read patters, and generally don't suffer heavily from being hosted on NFS.