Cool idea. Seriously!
A couple of years ago we had a similar thought - data analysts could do so much more with a hugely flexible platform. Imagine modelling + elt + analytics, notebooks, orchestration all in one platform.
Then we stumbled upon meltano - awesome! That's it! We've made some contributions, built various end to end models, considered adopting the ui as a project to enhance and along the way realised just how hard it is to make a platform straight forward enough for data analysts, esp, those who don't want to be engineers.
Meanwhile meltano themselves realised the data engineers needed better foundations too (my take by the way)
My advice, dive into the code. The UI has some of the things you need to create a SaaS and the Singerly guys have created a great platform with the meltano + airflow stack -
https://www.singerly.co
I have opinions on what would be even better! Happy to share if you wanted to meet on a call.