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.
Bitlocker keys for the OS partition are irrelevant because nothing of value is stored on the OS partition, and keys for the data partition can be stored and passed via AD after the redeploy. If someone somehow deploys an image that isn’t ours, it won’t have keys to the data partition because it won’t have a trust relationship with AD.