Describe the actual setting. Will players sit at a desk, hold a phone with one hand, use a classroom tablet, or interact with a kiosk? Screen size, session length, connectivity, and available input all matter.
Test the primary action early
Build a representative interaction on the intended device. Check comfort, visibility, responsiveness, and whether the player's hands cover important information. A desktop simulation can help development but does not replace physical-device testing.
Consider alternate input and control configuration. Some players cannot use a particular key combination or repeated gesture comfortably. The game's prompts and settings should remain consistent when controls change.
Separate export support from a good experience
An engine's ability to produce a build for a platform does not establish that the game is usable there. Performance, input, interface, audio, storage, and platform requirements need actual checks. Godot's documentation separates export workflows by platform, reflecting those different needs.
Agree a supported-device test plan and keep untested devices explicit. If the budget supports only one primary platform initially, make that a clear scope decision rather than imply universal compatibility. The best early device choice is the one that supports the intended audience and can be tested honestly.
Source: Godot export documentation.