Or between two Macs, one of which isn't signed into iCloud at all.Considering that's precisely the mechanism they came up with for that functionality (very much in line with other well-known features, like AirDrop and Continuity/Hand-off), it is highly unlikely that it will ever work across different IDs.
My work iMac wasn't signed into iCloud at all until a few months ago because I needed it to receive 2FA codes for signing into an Apple Developer account. It would literally not be signed into iCloud at all still if I hadn't needed that.