I don’t doubt you. Linux font rendering has been good enough for so long now that its surprising when people say its worse than some other system but I think it is still a reasonably common complaint so there has to be something to it. A lot of distros probably don’t have a very good font selection installed out of the box compared with proprietary systems and I am sure that plays a role.
My desktop has a 38" ultrawide and the pixel density is a lot lower than your dual 4k monitors so I want to do everything I can for font rendering and your post has got me asking questions. I am in the process of configuring a minimal, low distraction tiling wm setup for a bit of fun (also another nvim conf spring clean). I hadn’t considered changing the font rendering defaults.
I think I have all the fonts you list installed except for Hack. Inter is also a good one for UI. I don’t use Fira Code anymore for code/terminal but I keep it around. It is a nice code font with ligature support but it didn’t have an Italic variant and I like subtle use of italics in code and docs. Currently using Iosevka for mono but next week it might be something different.
Having comprehensive unicode language coverage on a free OS is amazing. I wish the font system was smart enough to hide Noto variants in creative apps but leave them available for browsers. There is a workaround to do that but its a huge pain. I wouldn’t delete any files managed by the package system. They will just keep coming back anyway. There are smaller collections of noto fonts in AUR that will satisfy the noto-fonts dependency which should keep KDE Plasma happy. They should be a straight swap if you are comfortable with an AUR dependency for a functioning desktop. The newer one is noto-fonts-main updated this year or there is an older noto-fonts-lite. Not tried either. Usual stuff about backups and taking advice from strangers on the internet.
Segoe might benefit more from the embedded bitmap or autohint settings than the regular open source fonts I am likely to use. Microsoft would optimise the hell out of it to take advantage of their proprietary, patented font rendering system. I wouldn’t be surprised if it rendered poorly with distro defaults. Its the kind of blind spot a lot of open source devs and packagers could easily have. Its probably packed full of embedded bitmaps for small sizes and proprietary hinting stuff that linux won’t understand.