Not really what you want, but the Awair Quality sensors have a local API that you can use to fetch the data (not local-first, as you asked, but it works locally

Not really what you want, but the Awair Quality sensors have a local API that you can use to fetch the data (not local-first, as you asked, but it works locally and you can disable internet connection) https://support.getawair.com/hc/en-us/articles/360049221014-Awair-Element-Local-API-Feature https://support.getawair.com/hc/en-us/articles/360049221014-...