Buy some ThinkPads or zBooks or Latitudes, give those to a subset of your affected users, then send the freed-up units to service. Repeat until all affected units have been serviced.
Then, when the time comes (soon?) to replace the 2015-2017 MBPs, consider whether you'd rather repeat that with future MBPs or buy something different that has on-site same-day service and user-replaceable batteries and other components.
You should know better than to post that suggestion in a thread full of Apple users with Mac OS lockin ... But don't worry, now my comment will be accompanying yours in the HN downvote afterlife :P
And for that, at least in this sort of situation, I'd expect a company to at least temporarily look into the various services that enable you to rent a MacOS device in the cloud for the moments you need it (usually app builds).
Then, when the time comes (soon?) to replace the 2015-2017 MBPs, consider whether you'd rather repeat that with future MBPs or buy something different that has on-site same-day service and user-replaceable batteries and other components.