Check that your APN settings are correct so that you can have mobile data , they are in Settings > About Phone
The Updater has to be updated before the main update, those files can be transferred to the phone with a USB cable and run them as local updates.
You can also access the internet through a USB-C to Ethernet adapter like this one, SIMPLE instructions to update to latest version of iodéOS on Brax3, please - #45 by dpourkesali
If you already have an adapter test it.
In case you update straight to 7.0 or through 6.9 you’ll need this update for the Updater, beta/UpdaterBetaIode6v3.apk · master · ota / ota · GitLab , you download the file and open it, it will ask you to trust it for installation.
The actual iodeOS Over-The-Air updates are here, brax3 · master · ota / release · GitLab , you need the *ota.zip files.
*ota.minisig are signatures for testing the integrity of the *ota.zip files
*ota.sha256 are checksums of the *ota.zip files for the same purpose
you can check those on your computer before copying the files through USB
After the iodeOS update you remove the update of the Updater, tap and hold on the
Updater icon > App Info > 3 dots upper right corner > remove update