Several specialized repositories provide pre-prepared root files for this specific model and binary:
: Features a downloadable ROOT A260G U1 8.1.0_Root .tar file specifically for this model. Manual Rooting Method (Recommended)
: Provides a ROOT_A260G_U1_Android 8.1.0 Oreo File from 2019 that requires installing the Magisk app after flashing.
If you prefer not to use third-party pre-patched files, the official and safest method is to patch your own firmware using the Magisk Installation Guide : Installation | Magisk - GitHub Pages
To root your running Android 8.1.0 Oreo with U1 (Binary 1) firmware, you can use specialized "root files" (pre-patched boot images) or manually patch your own firmware using Magisk. Direct Root Files (Binary 1 / U1)