seems like companies who know what proton is, would have no problem with it. some of their people would use it themselves.
companies who never heard of it wouldn't have any bad impression about it.
if they never heard about it but are wary/scared of everything they never heard of, might not be safe to work there. that's the kind of place that would test their workers' loyalty randomly, and not reciprocate any loyalty they receive.
afaik "lockdown mode" shortcut is a basic feature in android. it quickly disables fingerprint/face/etc unlock, temporarily.
it should still be present in some form in most versions of android since several years ago.
if you can't find it in your power button long press menu, check the Lineage documentation.
btw powering off the device should also force password/pin unlock on the next boot.