The CD that came with the device listed RTL8671B, but it's not on Realtek's website. Instead the manual points you to:
https://www.mytechkey.com/pages/driver
4.Bluetooth 5.0 Dongle
Driver Link:
https://www.dropbox.com/s/gwo9lz777i82f70/BT5.0%20Driver.zip?dl=0
| #! /usr/bin/env sh | |
| mkdir /etc/storage/stubby | |
| cat << EOF > /etc/storage/stubby/stubby.yml | |
| resolution_type: GETDNS_RESOLUTION_STUB | |
| round_robin_upstreams: 1 | |
| appdata_dir: "/var/lib/stubby" | |
| # tls_authentication: GETDNS_AUTHENTICATION_REQUIRED | |
| tls_query_padding_blocksize: 128 |