Everybody in a PC community is going to go to "build your own" by default, but it really isn't the only option.
It is true you won't match the price-to-performance on the Deck, but if you're willing to go a bit higher you can try a few things. For one, you can try to buy used. I would like to see a PC in person before I do that, but there may be options, depending on where you live. The good news is that upgrading from a Steam Deck anything with a dedicated GPU should be a nice boost in performance, so you can go for entry level or older desktop parts. If you don't mind a bit of bulk or have a convenient place to stash it you can also skip the whole mini-PC space, which is typically sold at a premium, and just buy a big old tower.
And then there's laptops. Used laptops devaluate a lot, which means you can find decent entry-level laptops with 30 series GPUs that will still outperform the Deck by a lot for a few hunderd bucks. Again, I'd like to look at one of those before I buy, but if you don't care about the screen quality or the cosmetics there are some affordable used options out there. Just... check the noise when gaming, because some of those sound like a hair dryer on high power mode.
As others have said, it depends on your budget and specific use case, but if you're using a handheld as a console attached to a screen you should be able to cobble something more functional together. Just maybe not as hassle-free or reliable.