@ccreed What app would the user use to contact 911 ? MSTeams?
If yes, we have customers who have exceptions for teams.microsoft.com which is not steered, but msg.teams.microsoft.com is steered (as well as all the other URL's)... uploads to Teams happen via Sharepoint, so DLP is applied to SPO and things continue to work fine..
If it's not MSTeams and some other app, I suppose adding a steering bypass for that domain/app maybe needed so that emergency folks can accurately identify the location of the user..
Hope this helps.