For more exotic parts you'll likely either need to get some break-out boards/fixtures to allow you to prototype. Most are too specialized to prototype well so you might need to make something simple/custom to suit your specific needs, and use that as a stepping stone to a final design.
Look at example boards on the AliExpress / Taobao scenes these might provide a quick / cheap way of understanding the bulk of any custom design.
Find a good proxy for what you're building, and write portable code, with reassignment of pins top-of-mind, so you can build/test code that's close to your final product whilst finalizing your own board design.
The STM32F2 is a rather old, and arguably dead-end product. Perhaps look at EVAL series boards if you can find them. Or honestly look at things which aren't already a decade old. The design and peripheral support is significantly better today on current STM32 families.
