Great writeup! You make a lot of great points here like getting subject matter expert involved early on and QA-ing with figma
I feel some of these important points are buried in the narrative and could be better emphasized if you made them a section heading.
What if the post is reorganized to have each lesson learned a separate section? That way, someone who is quickly scrolling through the article while they are waiting for the subway can see the main points.
An overarching comment I have is the text in the images is way too small. Even on the laptop, it's really hard to see what the images are trying to convey. They look like colorful blobs. I think the images contain really important ideas that would draw the readers attention and really drive home your points.
Another overarching comment is the run-on sentences and grammar could be improved. I use a tool called Grammarly which you can add to Chrome. It works in Medium in the browser to give you suggestions about grammar, spelling, etc.