The TinyWeb.pro service provides hosting for free and premium TinyWebDB databases.
TinyWebDB is a database format used in MIT App Inventor 2 and related services.
MIT App Inventor 2, Kodular (formerly Makeroid), Thunkable Classic (Thunkable X is not supported), AppyBuilder, Block2Code (formerly DroidMaker) and Hybro Studio
Not yet. Check the progress at DoesAppInventorRunOniOS.com.
It depends. You can choose Free, Pro or Biz plan for a database. See the differences at the "Compare" section and prices at the "Pricing" section.