This is exactly what I found when I tried esbuild a few months ago. I gave up and went with Parcel 2 at the time as I found it easier to get going (although there were teething problems with Parcel being beta at the time).
But maybe think about replacing the 4MB background video with a static image or something. It felt a bit overpowering for me (moves too fast) and it also doesn't scale right with the viewport leaving white text on a white background.
I've been doing exactly this too over the last few months. Safari iOS is so fast now on the iPhone 6s that I find the mobile sites faster than the apps in most cases.