Cliffski's blog is one of the only ones I follow that is still active. Not every post is on development progress, but enough that I find it worth following:

http://www.positech.co.uk/cliffsblog/

A couple of recent posts I liked:

https://www.positech.co.uk/cliffsblog/2019/12/16/stability-p...

https://www.positech.co.uk/cliffsblog/2020/01/14/trying-to-a...