I’m biased towards AMD in general, I just find them to be a slightly better value, but Intel CPUs are great too, and I don’t think they have any noticable issus on Linux.
As for other hardware, it depends. Just make sure to do a bit of research and compare multiple options, especially for something like the storage, motherboard, RAM, or power supply. It’s usually pretty easy to sus out which brands are trying to catch your eye with low prices and tons of RGB, and which brands are offering a great product (I will suggest Seasonic for a power supply. They aren’t the cheapest but the build quality is excellent).
No. I daily a Galaxy S23. I really like it except for all of Samsungs preinstalled apps that can’t be deleted.
A couple months back, I bought a refurbished OnePlus 6T (2018) to mess around with Linux and de-Googled Android, and guess what, my phone which is 5 years newer feels virtually no different. It does have a better camera, granted, but personally that doesn’t effect me as I do any serious photography with a proper camera anyway (also, I have to acknowledge that the 6T is slower as it’s not really a flagship phone like the S23, but the 6T feels comparable quality and performance wise to some mid range 2024 phones I’ve used).
Bottom line, unless we see more Apple M-style chipsets in phones, imo, we’re at a plateau. You could get a $200 5 year old phone and be fine.