What app making framework do you recommend to data scientists?

Communicating findings from data analysis is important for people who work with data. One aspect of that is making web apps. For someone with no/little experience with web development, what app making framework would you recommend? Shiny for python/R, FastHTML, Django, Flask, or something else? And why?

The goal is to make robust apps that work well with multiple concurrent users. Should support asynchronous operations for long running calculations.

Edit: It seems that for simple to intermediate level complex apps, Shiny for R/Python or FastHTML are great options. The main advantage is that you can write all frontend and backend code in a single language. FastAPI authors developed FastHTML and they say it can replace FastAPI + JS frontend. So, FastHTML is probably a good option for complicated apps also.