Separate persistent data and operating system partitions, ensure that every local network has small pxe servers, vpned (wireguard, etc) to a cdn with your base OS deployment images, that validate images based on CA and checksum before delivering, and give every user the ability to pxe boot and redeploy the non-data partition.
At that point why not just redirect the data partition to a network share with local caching? Seems like it would simplify this setup greatly (plus makes enabling shadow copy for all users stupid easy)
Edit to add: I worked at a bank that did this for all of our users and it was extremely convenient for termed employees since we could simply give access to the termed employee’s share to their manager and toss a them a shortcut to access said employee’s files, so if it turned out Janet had some business critical spreadsheet it was easily accessible even after she was termed