davem

my Rupa 88 Pro 20, wifi/bt chip is cdtech 208821c (rtl8821cs), with real 4g32 had no bluetooth with mmie4jbcu's dtb or the included box-demo.dtb. with a lil help from claude.ai, i mix mmie4jbcu's dtb with x96x6.dtb from another thread here. et voilá bluetooth is working after  
apt install armbian-firmware-full rk3566-box-X88PRO20.dtb

@MMorales@mmie4jbcu
i have the same x88 pro 20 clone like you guys, on the pcb is written "x88pro-rk3566-4d32-v1.0", which should state for 4gb ddr and 32gb rom i guess?

I installed latest armbian for station m2 with image-included demo-box.dtb, everything is working so far, despite bluetooth (CDtech-208821C=RTL8821CS). installed armbian-firmware-full but bt still doesn't work. 

Maybe usefull for just Linux-Users (i don't have a windows pc):

original loader didn't allow me to boot from sd-card, rkdeveloptool (or xrock or rdeveltool-gui) didn't work for me, so i used proprietary upgrade_tool for linux from rockchip:

https://docs.radxa.com/en/zero/zero3/low-level-dev/upgrade-tool

I downloaded this loader from radxa https://dl.radxa.com/rock3/images/loader/rk356x_spl_loader_ddr1056_v1.12.109_no_check_todly.bin and flashed it with:
sudo ./upgrade_tool wl 0x0 rk356x_spl_loader_ddr1056_v1.12.109_no_check_todly.bin
After that i put in the sdcard and it bootet straight (wait for min. 5 seconds) to armbian!