I don’t do a ton of estimation but an interesting new thing is asking a cli agent to estimate for you.

First impressions with this is they give really long estimates.

Also, due to coding agents, you can have them completely implement several different approaches and find a lot of unknown unknowns up front.

I was building a mobile app and couldn’t figure out whether I wanted to do two native apps or one RN/Expo app. I had two different agents do each one fully vibe coded and then tell me all the issues they hit (specific to my app, not general differences). Helped a ton.