Most of the "professional" microcontrollers have complicated flashing schemes, expensive bespoke IDEs, and limited language support. Treating a lot of that like a moat around their products.
I find it remarkable that they haven't tried to make all of that easier. Any board with arduino support is easy to start using, with pared down c++, boards similar to the micro:bit support micropython and javascript as well as a few others, and a ton of modern development boards have UF2 support.
UF2 is a step change in how easy it is to flash a binary onto a microcontroller. You hold down a button before connecting it to a USB port, and then it appears as a USB drive for you to drop a file onto, once it's done "copying" the board is flashed and will run your code as soon as it resets.
If you want to gain familiarity with a board, you can drop a .uf2 file with a REPL on it and run code on the board a line at a time.