The screen resolution is high compared to steam deck for sure, but about the same as 7" ROG Ally (1200p vs 1080p), and dpi is slightly lower than Legion Go. Remember that your 6.3 inch phone, also a handheld device, probably has a higher DPI than this.
I also don't understand the phone comparison, this is a gaming handheld, very specific purpose compared to an all-rounder device. Please elaborate
> if you can't drive this
I assume your use case is playing Triple AAA games. But there are others such as Indie games and emulation which both benefit from higher resolutions. Especially in emulation a higher resolution will allow you to do integer scaling for a greater number of systems etc.
7-inch FHD+ (1920 x 1200, WUXGA) 16:10, 500nits Brightness, 120Hz Refresh Rate