A mobile device can never be the primary device, computer system must always be the primary. Resetting up your mac to use the exist syncing date (and that assumes you are using MD 2017) would only make that also into a secondary device, turning that into the master necessitates effectively breaking the syncing setup and thus the need to recreate it and in reality that is a disaster recovery approach that should only be used if all else fails. It could well work but you are pushing it into an area it is not designed to handle.
Even restoring the master from a backup should not be assumed to allow the more recent data from the mobile device to be able to be synced to the new install, it may well do so but should not be assumed to.
I do not believe that the approach you are planning can be guaranteed to work. Using a mobile device without a system that is considered a full system (MacOS, Windows, Linux) is not a supported configuration. A mobile device is always considered to be a companion app.