The adapter I linked to goes from HDMI (input) to USB-C DisplayPort Alternate Mode (output). The micro-USB connection is just for supplying power to the adapter (being an "active" adapter, it needs power). Adapters or cables from micro-HDMI to full-size HDMI are easy to find.
You don't need a HDMI to Thunderbolt adapter (I don't think such an adapter exists in the first place). You just need HDMI to USB-C. The Studio Display accepts video input via Thunderbolt and USB-C, but you'll have to use its Thunderbolt port in both cases. So, to use the display with the RPi, you'll have to disconnect your Mac or look into a switch (see this thread).