[Unit]
After=bluetooth.service
Description=Bluetooth service
[Service]
ExecStart=<your-process>
Group=root
StandardInput=tty
TTYPath=/dev/tty2
TTYReset=yes
TTYVHangup=yes
Type=simple
User=root
Many thanks, this is the only workaround which actually works for me. Just needed to execute simple command sudo btmgmt SSP off but it was pain in the ass with systemd+btmgmt.