Most of the documentation about this comes from TI. They have somewhat good documentation and examples, the problem sometimes is finding them. For me, the more practical way is to go to TI github and found their MCU+SDK for the AM62 [1]. On this repo has their HAL, BSP and some examples for the M4F/R5 cores. For rpmsg, you can look on the IPC examples [2]. You will need to dig a bit to get how they organize things.
For the Linux side, TI call it Processor SDK [3]. In the development portal [4] there a lot of nice things you can explore (worth it) and on the SDK Guide you can find more info on remoteproc in U-boot [6] and remoteproc/rpmsg in Linux [7]. The Academy [8] is nice too and have some “guided” examples on booting remote cores and ipc communication.