Perhaps it is beyond the scope of what you’re looking for, but I just streamed an online presentation to YouTube and Facebook using OBS Studio, which is a free, open source broadcasting application. It lets you cut to different views, called “scenes.” These scenes can include different sources, such camera angles, apps or windows on your Mac, media sources, browser sources, images such as overlays, or any combination of them on the screen at the same time. You can add overlays or different effects to these scenes, and transition between them. It makes for a more slick presentation, and I didn’t find the learning curve to be too bad after watching a few YouTube videos.
Even if you couldn’t stream directly from OBS to whatever system the meeting is using, I believe there is a “virtual camera” plugin which lets you pipe the OBS output into other systems, such as into Skype, Streamyard, or any app where the virtual camera isn’t blocked (the latest Zoom update, for example, no longer supports virtual cameras without a hack).
I used Keynote along with OBS for my presentation. Keynote wants to take over all screens, so I ended up using Keynote on my iPad, and AirPlayed that to a second monitor using an app called Reflector which turns your Mac into an AirPlay receiver.
My journey down the OBS rabbit hole started with a simple desire to briefly have myself on the screen, with overlays, etc., at the very start and finish of the presentation. It turned out to be lots of fun.
And I’ll second the above comment about livening things up. My Keynote contained almost no words, but instead used animations and images, etc. that flowed along with me as I was talking. David Sparks has a very good Presentations Field Guide which discusses things like this.