Few questions here:

First, "I want a Framework". Framework is REALLY overpriced for what it is. I haven't run the math since Liberation Day but generally the following shows that Framework actually doesn't make sense for a consumer:

Let N be the price of a brand new Framework laptop, M the price of just the motherboard of the same quality tier, and P be the price of a similarly specced laptop at Best Buy or whatever.

For upgrading a Framework to be cheaper than just buying another laptop in however many years, N+M < 2*P. And the math usually comes out as it being a few bucks cheaper, at best. Which ALSO assumes that your keyboard, monitor, etc all remain in good condition and that Framework don't change their form factors or anything.

Frameworks only make sense if you are in an environment where you burn through laptops quite quickly. So... a corporate environment (where they still have fairly shite support) where you will just give Fred a new laptop and then repair the one he ran over with his car later. And from when I actually ran the numbers for a company... the existing solutions were MUCH cheaper and the better ones actually have strong policies towards how they recycle e-waste. I could imagine a very small business threading the needle and making it work but... yeah.

Second is "Can I use a Steam Deck as a conventional laptop?". Conceptually, yes. Desktop mode is just KDE Plasma (best desktop!). That said, the Steam Deck is built, first and foremost, as a gaming device so your lock screen is basically a shitty version of a phone lock screen with a touch screen that you probably only use when entering your passcode. It is also a high profile distro to attack. So... do yourself a favor and do not put any secrets (other than your Steam and GoG and whatever credentials) into that. I am not sure if the other Handheld Form Factor Gaming PCs have better security but I doubt it.

I definitely use my Steam Deck for a LOT of around the house debugging and even when I visit family or less tech savvy folk. When I don't need to enter data and just need to be able to test a network connection or see a log? It is actually really nice. But I wouldn't write any code or check my accounts on one.

So lastly we have "What should I do?" or, more accurately, "What would you do?".

Personally? Get a cheap beater laptop (which it sounds like you already have) as your daily driver. Unless you are doing heavy local workloads (video editing or, I guess, compiling LLVM constantly) you don't actually need all that much oomph in a laptop. And most of those workloads are best done on remote systems (of which you should have lots of access to as a college student).

As for gaming? The Steam Deck is an excellent choice and is what I would recommend since you'll probably actually come out ahead on buying a Deck+Laptop versus a Gaming Laptop AND you won't have to schlep that monstrocity around just to toast your crotch while you use it.

But... depending on how much gaming you do and how ideological you are... nVidia Geforce Now is actually REALLY REALLY REALLY good if you have even a decent internet connection (and you are at uni so you will have a good one). 10 bucks a month isn't cheap, but considering a Deck starts at 400 USD for the LCD... 40 months or so to break even.