I've spent the last decade in telecom engineering - RFDS reviews, SOW/BOM work, FTTH and GPON deployments across the US carrier market. The whole time, I kept doing the same dumb thing: putting my phone down somewhere in the house, switching it to silent, and then standing in the middle of the living room completely unable to find it.
Find My Device works when the phone is online. Mine often isn't. Asking Google Assistant to ring it works when the ringer is on. Mine often isn't. The one thing that always reaches my phone - the thing that worked when everything else didn't - was an SMS from any friend's phone. So I built a small Android app that listens for one specific word in incoming texts, and rings the phone at full volume the moment it sees it.
That app is FindMyPhoneSMS. It was a personal tool for two years before I decided to ship it. Monaï Telecom - the engineering company I co-founded - signs the builds and operates the licensing backend.