Hey there. I think that’s currently the only workaround. I have actually been a longtime user of Outlook for Mac and only recently decided to try out Apple Mail (I also work in an organization where everyone uses Outlook as we have an Exchange Server for email, calendars, etc.). The font thing was my one hang up as well. I posted about setting the font in outgoing messages and got some strong opinions that I “shouldn’t” do that. See this thread: Apple Mail fonts/recipient's view
Given that I am used to Outlook for Mac, and don’t really have a hang up with Microsoft software on performance or aesthetic principles (I have to use Word and PowerPoint as well), I’ve just decided to stick with Outlook for now.