Yes, it’s possible. Just copy the blockchain folders (blocks and chainstate) from your friend’s PC into your Mac’s Bitcoin Core data folder (~/Library/Application Support/Bitcoin). When you open Bitcoin Core, it will detect the copied data, verify it, and then continue syncing the remaining blocks. This way you don’t need to download the whole 700+ GB again.
thank you very much, I couldn't figure it out by myself,
unfortunately I don't have enough space in my main hd too... do you believe I can still go to the bitcoin core settings and change path (to external hd) ?
otherwise I will have to reconsider my plan..