Ah wait I missed that UART attachment needed for the onboard Bluetooth here. Please try this:
sudo curl -fo /usr/local/bin/hciattach_opi 'https://raw.githubusercontent.com/orangepi-xunlong/orangepi-build/refs/heads/next/external/packages/blobs/bt/hciattach/hciattach_opi_arm64'
sudo chmod +x /usr/local/bin/hciattach_opi
cat << '_EOF_' | sudo tee /etc/systemd/system/sprd-bluetooth.service
[Unit]
Description=Spreadtrum (sprd) Bluetooth support
After=bluetooth.service
[Service]
RemainAfterExit=yes
ExecStart=/usr/local/bin/hciattach_opi -n -s 1500000 /dev/ttyBT0 sprd
[Install]
WantedBy=multi-user.target
_EOF_
systemctl daemon-reload
systemctl start sprd-bluetooth
Please also check which kernel modules are loaded:
lsmod
sprdwl_ng and sprdbt_tty somehow did not want to load both via /etc/modules-load.d, or the order was relevant. And after the need for the UART-attachment, I am actually not sure anymore whether sprdwl_ng (WiFi driver) is really needed or not.