Like already mentioned here I’m using an older Moto G (3rd Gen) running Android 6. Cheap, small, robust, waterproof and less power consumption than newer “high end” devices.
For mobile data the Moto G is connected to my main smartphone (Huawei P20 Pro) via Bluetooth Tethering. The Huawei stays save in my jacket’s pocket (I would never consider to use it on my bike).