What games does your daughter play and what platform does she play them on? (Steam/Xbox/Epic etc.)
The Steamdeck is a fantastic device for playing Steam games and gives an almost console like experience for those games, the downside is it's not great if you're wanting to play non-Steam games. There are some workarounds for other stores but they can be tricky to implement depending on how tech savvy you are and in some cases not possible, the likes of Fortnite won't run because the anti-cheat isn't supported. The performance is obviously limited as well so playing higher end graphical games is not going to be possible, Steam have a really handy rating system on the game pages (which is also a filter on the Steamdeck) which shows how well a game will work on the Steamdeck. If you look on a game page on Steam and scroll down the right hand side, you'll see a status for the game under Steamdeck compatibility and if you click learn more it will tell you of any issues with the game, for example this is the Halo Masterchief Collection on Steam:
The Master Chief’s iconic journey includes six games, built for PC and collected in a single integrated experience. Whether you’re a long-time fan or meeting Spartan 117 for the first time, The Master Chief Collection is the definitive Halo gaming experience.
store.steampowered.com
You'll see it's listed as playable and it warns that it may need the on screen keyboard and some default controller configuration. If you look at Ball X Pit:
BALL x PIT is a brick-breaking, ball-fusing, base-building survival roguelite. Batter hordes of enemies with ricocheting balls and gather the riches of the pit to expand your homestead, generate resources and recruit unique heroes.
store.steampowered.com
It instead gets a green tick with no issues on the Steamdeck.
There's quite a few alternatives but I'd say the main ones are the Lenovo Legion Go series and the Asus ROG Ally devices, there's quite a few in the ranges of each. The main difference they offer is that they come with Windows instead of SteamOS (although some of the Lenovo ones now offer SteamOS as well) but that is a mix of advantages and disadvantages. It gives the devices broad compatibility so they can easily play games on any store and also support any anti-cheat software, they're also to reconfigure to do as you want since they are just a Windows PC. These other devices can offer better graphics performance as well with the Steamdeck still running on its original relatively low power hardware although I don't find that a huge difference for gaming on the device itself. However for gaming the Windows devices are less user friendly because it is still Windows, Microsoft are slowly moving towards making a proper gaming interface and the device makers have tried to make their own software to smooth the experience but it's an area SteamOS is much better, also SteamOS remarkably offers better graphics and battery performance.
Personally I started off with an original Steamdeck which I found an amazing device and the idea of a portable gaming Linux device seemed so laughable, it was incredible they'd made something that worked so well. The couple of issues I had was that I found was that I wanted to use my Xbox Game Pass and play games that needed anti-cheat with Epic Games Store, also I found the 7in screen on the Steamdeck a bit on the small side for PC games which didn't always scale well so I bought the original Lenovo Legion Go. It's been a good upgrade and I'm quite happy with it however with Microsoft tanking the Xbox platform I've mostly moved back to Steam these days, having the choice now I may not have changed to the Lenovo.
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As long as the games your daughter plays and wants are on Steam and work with the Steamdeck I think it's a good choice.
