Can we revisit this https://forum.liquidfiles.com/threads/outlook-web-access-integration.482/ Switching to the modern framework would enable the add-in to be deployed to users via M365 and make it available to users using Mobile clients and OWA.
The support for the new web Outlook add-in should be implemented in the next major LF version 4.1. Currently there is no eta for v4.1.