Power Apps grid control will support offline in GA
Previous grid controls available for model-driven apps become read-only when your device is offline, which removes the important ability to perform inline editing of records in the grid. That limitation will be lifted with the new Power Apps grid control, as this grid now supports editing when offline.
Preview of the Power Apps grid control was announced in earlier this year (see Inline editing, modern browsing, and more with the new Power Apps grid control | Microsoft Power Apps), and this grid is expected to transition to being generally available in the next few weeks. Note that the GA release of this grid will not include inline editing on mobile devices; that functionality will remain in public preview for the time being.
Editing while offline

Subgrid editing while offline

Next steps
Start testing the Power App grid control in your non-production environments! See Power Apps grid control - Power Apps | Microsoft Learn for details on how to configure this grid.
Stay tuned for the GA release and details on other new capabilities available with this grid control!
Important!!!
Power Apps grid are still in public preview and should not be used for production scenarios!