Late to the party but I’ll share a bit of my experience. Many of us in the iMapInvasives network are making use of iNaturalist for a source of invasive species observations, and encouraging folks to use iNat to report things they think might be invasive. I wrote a web article about one of our early detection successes for this, at https://www.imapinvasives.org/storyorinaturalist.
The iNat invasive sightings are also really good at filling in places that managers aren’t always working/looking (or lacking funding to do). For the more detailed info on management and follow-up, we point people back to iMap for the additional fields/features there. But iNat is a great source of obs.