My suggestion is that the “Find My Device” feature should use passphrases instead of secret codes in the future. “Find My Device” is a powerful tool for locating your device, but there is also a risk of compromising your privacy. That’s why I don’t want to carry around slips of paper with the secret code unnecessarily or give them to other people before I loose my smartphone. However, I can’t easily remember secret codes—passphrases, on the other hand, I can. So here’s my question: Would it be possible for Find My Device to generate passphrases or even allow users to enter their own passphrases?
Trying that feature for myself right now and am struggling with the issue, that GPS has to be turned on, and can’t be turned on by the app itself.
In regards to your suggestion: The privacy risk this feature poses, as well as storing an unidentifiable code in other locations, is probably quite low, at least relative to the huge privacy and security issue that comes with being connected to the mobile phone network at all, that still uses SS7. You cannot be secretly tracked via this specific feature, since all SMS are visible to you. You can reset the code any time, which you probably should, after you used one.
You can be secretly tracked simply via your phone number by any person, who is determined enough to pay some shady phone-service-provider for access to SS7 though.
Personally I store it in my purse as well as the keepass-password vault, that is synced across my devices. If you store your passwords all inside your phone without any secure backups, or you reuse pws or passphrases, you might want to change that.
All of this can be solved using Tasker. Basically you can implement your own “find my device” with Tasker. Upon receiving an SMS with a given passphrase, Tasker can toggle on the GPS, and send current location back to the phone that sent the SMS. You can also let tasker max out the volume and if you call back the phone, it will ring on max volume, which helps to find it. Pretty convenient.