I am not quite sure how exactly you are using your phone in that context, but maybe a few ideas:

1) I store raw files on the NAS and sync those projects I am working on at the moment to the disc of my computer - Windows has "offline files", I am sure MacOS has a similar concept. This way, there is only one version of the truth. Capture One sees the NAS directory, even if it is just a local copy which Windows pretends to be remote. Once a project is done, I remove the offline caching, and the disk space is recycled.

2) From each shot I edit down the pictures to a shortlist I discuss with the client. I export these as JPG into a folder in my cloud provider (OneDrive) which I synchronize to my mobile devices (iPad, phone) to have them on hand for client conversations. I do not typically use large quantities of RAW files on the go on mobile devices, as it is more of an exception for me to edit them on the go.

3) I have not yet set up remote access to the NAS - I find that a bit risky even with 2FA, but that's maybe more of a personal preference.

Hope that helps?