one option: esp8266 module with AT firmware 1.7.1 and my WiFiEspAT library in Nano BLE.
Thanks Juraj, that repo looks amazing, have you tried it yet with the Nano 33 BLE?
Microsecond delay will not be possible. This only works with the new NINA modules where the firmware was developed to allow both protocols to run at the same time. If it takes you a few years to get this working you might be able to switch to a board with the NINA-W15 in a years time when somebody creates a new Arduino. Most if not all development you do now can be easily transfered.