I have a Pixel 7a with GOS in airplane mode, with WiFi only. My old phone with the sim inserted is on Lineage OS and hasn’t fully (has a case of occasional ghost touch) died yet. I only use the old phone for cellular telephony.

Yeah, it doesn’t scale. Most of the surveillance (legal intercept, SINA hardware on ISP) and injection of government malware will be through the hostile network. People who run a tight ship will have a small attack surface.

You should switch to opnsense, not pfsense.

If corporate wants something, they can provide corporate phones. I keep company and private strictly separate.