Just a further wrinkle on this approach:
I have worked in Powerpoint for quite a while, and I find it allows me a great deal of flexibility and power in preparing graphics [on a slide.] I often bring a photograph or strictly graphic image into Powerpoint onto a slide, and then edit it heavily - arrows, text, animations, transitions, etc etc. I do this in Powerpoint because I have become familiar with it - much more so than Keynote.
I find Keynote's architecture rather baffling, right down to what menu-options and buttons are labeled. Very unintuitive to me compared to Powerpoint [which I taught myself by doing.]
Both Keynote and Powerpoint allow one to record a slideshow of {slides plus audio}, and both will export at 1080p which is good for my work [photography, so detail is important. Empirically, I have found 4k is unnecessary for me.]
BUT… and this is a BIG BUT, using the Mac version of Powerpoint you you cannot export the audio track of a recorded slideshow. …Riddle me that…
So, I mostly [90%] create my slides in Powerpoint, and then I import them into Keynote which is 'almost' seamless.: drag & drop, immeidately save into .key format. Sometimes I find a few changes/distortions introduced by the transfer, which I have quickly learned how to edit in Keynote, and sometimes I make a few tweaks simply because I have new idea after looking at the slides anew.
Then I record the slideshow+audio in Keynote, export it as a movie @ 1080p, import that into my iMovie project and do my editing and rendering/creation of the final movie as a .mp4 movie.
The workflow in actuality is much easier and smoother than it sounds in this description, and I consistently get excellent visual product with very clear audio. [The audio level in even short clips can in iMovie pretty easily be modified.]
Hope that helps lower the barrier to your at least trying this approach. For me, being able to quickly go back and tweak a graphic [slide] in Keynote [or if necessary Powerpoint] is for me a huge advantage. I find that I get improved ideas about how visually to present my instruction during and after reviewing my movies so I want an easy path to revisions of the graphics. Also, re-recording a short clip and inserting it in the body of a 'lecture' is very easy in iMovie.