For everyone that need a working Bluetooth on OPi3 i've found a fast solution:
I'm using this version of Armbian:
Linux orangepi3 5.3.1-sunxi64 #5.98.190930 SMP Mon Sep 30 02:43:17 CEST 2019 aarch64 GNU/Linux
There is no need to use extra overlay or enable uart1, all the configurations are just present on sun50i-h6-orangepi-3.dtb.
You can use the procedure indicated on previous post:
and change the patching line to:
/usr/bin/timeout 20s /usr/bin/brcm_patchram_plus --patchram /lib/firmware/brcm/BCM4345C5.hcd --no2bytes --bd_addr $MAC_OPTIONS /dev/$PORT 2>&1
Bluetooth must start without problem ....
I've seen that a patch for bluetooth on OPi3 is just developed :
https://lkml.org/lkml/2019/8/23/320
but i don't known if and when it will be included into mainline distribution.