Is it posible to add a new account/user for ssh, to the pi sd card directly in balena

I’m need to add ssh access to a device I cant remember the password to/ dont have the password , is it possible to add a new user using by perhaps adding a file to the sd card … like you can with rasprian os. i own the device a hotspot but would like to add a few extra features like mqtt and have a restart option perhapes using pitunnel ?? the manufacturer has made it difficult and uses port 2222 for updates via ssh with there own password etc i dont know … i have the device in front of me and can access the sd card … as i dont know the password i cannot log into belena directly to add the user etc ive looked in the config.json and found ssh keys /ssh-rsa and api keys user id device id can i use any of that to achieve my goal

In order to gain access to the device using SSH, you can add your public keys to the config.json as referenced here: Configuration - Balena Documentation
Next, use the standalone SSH client to access the device as referenced here: SSH access - Balena Documentation
Hopefully this helps you get access to your device.