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

Hello,
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.