I did something similar once, but integrated everything RESTful into nginx which connected to postgres directly, which ran triggers with JS. What I didnt like about it is being bound by max connections to postgres, and then blocking postgres thread when running javascript in it. The parallelization story just wasnt competitive enough.
Oh it's Yuri Rashkovskii, one name I actually remember from the olden times.
I think you have a good project on hands, happy to see you could establish it as a tech startup. Over the years my mind keeps wandering into this place where an apps are much tigther integrated with the database. Where a full class of engineering tasks (and bugs caused by them) is eliminated completely. I'll be checking your progress.
Is this something that omnigres addresses?