Yes, it will work, but not ideally.

Setup via Bluetooth from your phone ✓
Will mow automatically once programmed ✓
BUT: No remote monitoring, no alerts if problems occur, must walk to mower to change any settings

Of course, you will not be able to use the iNavi feature, and will need to have the RTK base station set up.

For 3,000 sq metres with poor signal, it's risky - you won't know if something goes wrong unless you physically check.

Recommendation: Consider adding WiFi coverage to your garden first (outdoor extender/mesh system).

Hope this helps.
Mark