I've been using the Legion Go as a gaming PC for a while now when I'm away from home and also as a desktop. I bought a docking station on Amazon and connected it to an external monitor via HDMI. I am very satisfied, everything works very well and quickly, depending on the connection of course. Hotspot via iPhone works best externally, as most WLANs outside are not very fast. I mainly play World of Tanks, which requires a lot of resources, and have never had any problems. I don't get on well with touch control (screen), so I usually use the device with a Bluetooth keyboard and mouse. Since my game is played with a keyboard and mouse anyway, I don't need the pads much, so I can't say too much about them, except that they feel good and are good. All in all, I'm very satisfied and would buy it again. I don't have a comparison with Steamdeck or ROG, but I finally decided between the three in favour of the Legion Go because of the great display, the size and the testimonials I read at the time.

Ciao WungaBunga
I've been using the Legion Go with an eGPU on an external ultrawide display for a few months now. Without the eGPU, it lacks the necessary power to play games smoothly, but if it's just for web and other light tasks, you can leave out the eGPU. The docking station also works perfectly for transferring to monitors.
The only alternative to the Legion Go in terms of power would probably be the ROG Ally X due to the 24GB RAM. Ally software is also more mature as it has been on the market longer. Steamdeck (OLED) the "weakest" of the three handhelds and also not on Windows but specially made UI for the deck (best UI but limited compatibility due to SteamOS).
I chose the Legion Go because of the monitor, 8.8" is simply a dream! The 7" of the Allys would no longer be enough for me. The performance is almost as good as the Ally X.
If you want more portability/smaller form factor and better battery life then I would recommend the Ally X. If you prefer a large screen then the Legion Go. Just gaming and a handheld a la Nintendo Switch, then the Steamdeck.
LG

Basically it is a tablet with windows 11 and a joypad attached to the sides, with all the advantages (or disadvantages) of windows.
So, unlike Steam Deck, you can install all the stores (steam, GOG, Epic Store, ...) but also services like Game Pass or Geforce Now.
Of course, you don't have the "console" experience that Steam Deck has, but you will have to fiddle with windows a bit.
Substantial difference with Ally is the display, bigger and more resolved but less optimised for gaming, and the software a little less polished than Ally's, but still very functional.
I don't think it will reach the levels of a mid-range PC, on the contrary, but there are a lot of tricks to make it run at high FPS with a good graphic detail, such as using frame generation programmes (native in AMD settings or lossless scaling), playing a bit on upscalers and, if you have a good connection, using streaming services such as Geforce Now, Game Pass itself, etc.
If you are at home via Steam you can run games on your PC and play them on Legion GO.
Plus, being basically a Windows PC, you can plug in any compatible peripheral, mice, keyboards, screens. And unlike Ally you have natively two USB C ports.
And of course you have windows multitasking, so listen to music in the background while playing games, use other programmes etc.