Concept have a pace to watts calculator - https://www.concept2.co.uk/indoor-rowers/training/calculators/watts calculator
So 3k in 11:21 is a pace of 1:53.5 per 500m which translates to 239.4W.
My N=1 is that in terms of estimating FTP there is a bigger drop off from 20 to 60 minutes than there is in cycling. But maybe that’s because when I was rowing all of our races were shorter than 20 minutes so we simply never trained to go hard for longer than that (lots of long steady state stuff though, with hindsight it was a pretty polarised approach).