Question: Who are the key players in Full Site Editing?
Answer: WordPress is developed by many hundreds of contributors, some of whom concentrate on Full Site Editing. Many of the key developers are sponsored by their companies to work on the projects for anywhere between 5% of their time to many more hours than a normal working week.
You’ll find them on wordpress.org, Slack and elsewhere.
There are also the theme shops who concentrate on building themes for the end user and agencies who develop themes for their customers.
Then there are volunteers who support WordPress in their spare time.