I would like to be enlightened myself if RPI,BMAD or any spec-driven approaches actually worked for any mid/large scale projects, without wasting millions of tokens of course :)

Real spec driven uses no tokens

True that, and this time Github AI actually have a useful answer to check for githubstatus.com

As much as I love .NET. I would like to see the whole libraries ecosystem being sustainable again. A recent license changes from all my favorite libraries just made me hesitant using .NET for actually build a startup TBH

I would also like to see the whole ecosystem being sustainable, financially :)