Esp32, ai-thinker based in Shanghai offers the s2 & s3 chips popularility following its smash hit 8266 (serial bluetooth & wifi) is skyrocketing (from zero demand).. Lots of fresh projects in the past decade, you are correct!
Initially hamstrung as a startup they had Low chip yields, poor software support, lack of designer fluency compared to more established stm, nxp, ti are western brands. Their chips are overpowered for many small embedded products, underpowered and more difficult to dev/deliver software compared to a raspberry pi or custom odm arm chip running posix linux & docker. Ai thinker wins best in class on processor power & power, but most electronics are continually plugged in (not battery) so that advantage is not huge deciding factor unless you are doing sustainability engineering and you realize how much more power+carbon offsets you required to approach carbon neutral.
Ai thinker is popular in shenzhen China ai market oriented contract design & manufacturing in China military-defense products & dystopian monitoring than the western chips. Those products, found only on the mainland are not ones that most ycombinator people are familiar with.
Ai thinker/espressif would design ref boards & interfaces, but of course they are not guaranteed of actual unit sales. Ti, nxp, even amtel have industry targeted chips that are certified for automotive, etc. Whereas ai thinker lacks the equivalent global sales force (and emb. Systems people have job security as long as they don't rock the boat and make their teams learn new ecosystems)
Also a lot of new embedded products in industry aren't new, the software is very old, much older than the the chip.
The avg. Embedded systems devs learned design pre-iphone and its a 9-5 job, they are told what to do, and usually aren't starting from a greenfield since the devCost burden & supply side risks are higher changing chip lines (and dev environments), when viewed from a profitably lens.
Disclosure: My company specializes in esp32 & stm ag-tech.