Most tech people are just better than average at looking stuff up :)
I have never used Zorin, but it looks good - it’s based on Ubuntu but tweaked to be more friendly to Windows/macOS users. If it’s working for you, that’s what counts. There’s a lot of documentation around Ubuntu which should apply to your system.
“Barebones” usually just refers to a machine that is not complete, missing CPU, memory, storage, for customization. I assume you mean it’s a basic/low-end configuration. Still, it seems to be a fairly recent generation of hardware. If you have a spinning disk, you’ll see a huge performance increase by upgrading to an SSD. You can get a 512GB SSD for $25-35.
If you look at minimum/suggested requirements for almost any distro, I think you’ll be comfortably above that. I looked up the laptop and it seems to have an AMD APU (similar to what’s in a Steam Deck), optional NVMe drive, 8-16GB DDR4, WiFi 5… I’m running Ubuntu 23.04 on a 2015 laptop and it’s fine, no difference at all from a current gen in Google Workspace.
That should be an easy fix though, you can get a 512GB SSD for $25-35. In fact OP said they were doing this because the original drive failed. You’d notice a huge difference going to flash.
That isn’t an old laptop, it shouldn’t have any bearing on which distro you pick. Ubuntu is solid, I’ve been mostly happy with KDE Neon. Web experience is going to the same across the board. Will you be gaming?
Is he accepting medical treatments that require non-free software? Serious question, from what I know of him he would rather die. I don’t know if that changes when you’re actually faced with it though.
What do you mean by “better”? Sound is very subjective, can you try to be more specific?
Of all the tools you mentioned the only thing I use is tlp on laptops. I’ve never felt the need to run something like stacer, it looks like it claims to do what you’re looking for, beyond that I would just address your specific concerns. If you have a job that’s running periodically that consumes too much CPU maybe you should schedule it for when you are not using the computer, or see if you can throttle it.
Uninstall apps you’re not using if your laptop is overloaded. Maybe consider a buying a new one if you need more performance or battery life.
Keep in mind Linux is not Windows and modern Windows doesn’t really need all the “optimization” people think it does anyway.
What specific issues are you having?
I’m really tempted to order a StarLite, and I feel like that would be the best fit for you, but understand the hesitance to be an early adopter. Maybe you can pick up a used device to tick the boxes and order one later.