I get the appeal of handhelds for games that can be played primarily on a controller (platformers, racing games, etc). Problem is for many older games and entire genres (RTS, FPS, Commandos-like strategy games, 4X, point & click adventures, text adventures, etc), I find trying to force them to 'fit' onto a controller just to fit the device's form factor plays far worse than a keyboard & mouse they were designed around. Trackpads on handhelds are still slower vs mice for rapidly selecting things as they're always been on laptops. You can get away with that for slow-paced non-actiony point & click adventures, less so with RTS's. AntiMicroX can translate controller input to a "virtual" keyb / mouse, but older FPS's still play far worse when all the "under the hood" controller 'cheaty' code quietly placed in modern FPS's (eg, controller auto-aim, snap targeting, enlarged enemy hitboxes, weapon wheel selection, etc) is missing.

Touchscreens work best for mobile games designed around them (eg, Bejeweled) because they usually have large oversized UI elements ("It looks like a mobile port!") for precisely that reason. Anyone who's played around with Magic DOSBox on a similar sized 7-8" Android tablet can see for themselves some games can work fine whilst other games can technically "run" but simply aren't that enjoyable to play in practise in the face of issues like non-scaling UI's (hard-coded for 92ppi = on a +200ppi HiDPI 7" screen some UI elements can shrink to being absolutely tiny and barely readable), or selecting individual units in say Age of Empires / Lemmings, etc, when they're far smaller than the finger you're trying to 'click-tap' them with.

Workarounds for text heavy games like having to keep toggling an on-screen keyboard overlay (to type) then put it away again (so you can see what's underneath) on every key entry can get very annoying very quickly vs having a proper "hard" keyboard in text heavy games. And although you can solve half these issues by plugging in a dock, then plugging in a keyboard & mouse / external monitor into that dock, it's then significantly less portable than the marketing brochures suggest.

I looked at handhelds with serious consideration to buy one, but with a wider taste in / preference for older games than the usual narrow slice of only the newest action-adventure AAA's they typically get demo'd / reviewed with, personally I'd rather have a 14" laptop / detachable Windows tablet with the same 7840U / 8840U APU (eg, Minisforum v3) that does a whole lot more outside of just gaming (14" vs 7" screen difference makes office, web browsing actually pleasant) for little extra weight that you can still connect a compact Bluetooth controller (eg, SN30Pro) to anyway but without it being forced as the "expected" input device for a lot of older K&M-centric games that simply weren't designed around 2 joysticks.