TF2 dropped Mac support officially.
I have not tried running TF2 on my Linux but I have heard across numerous forums, youtube channels, etc, Linux gaming is pretty good now. Valve's proton layer is a few years in by now so I don't doubt it. Your bigger sandbag might be your hardware. I've used a 290 on Windows for like 10 years now and its pretty old but I can just barely get by in TF2. Again, haven't tried it on Linux yet though.

I've been running TF2 on linux for many years, never had a single issue, all the valve games are built natively for linux. installing it is piss easy nowadays, literally every distro has a graphical installer

You can choose both.
I don't own Mac, so I cannot help you debugging stuff, but the wiki dedicated to gaming on mac shows that it's possible to play tf2 on mac. There is also a guy in the benchmark thread who uses yearly paid VM software on the Mac M4. I don't recommend VMs, because they require reservation of CPU cores, RAM and GPUs, so it's more costly than compatibility layers, but depending on the state of compatibility layers on Mac, you might (or not) get higher fps. This post on r/macgaming is a nice overview of software using compatibility layer, but be aware that whisky is abandoned(recently so it still works, until it won't), there is one-time payment for crossover, and Kegworks was renamed to Sikarugir. Sikarugir(Kegworks) is apparently most active project and this video should show you how to install it. Any non-native Mac game is also subject to the issue described below.

As for your PC, before choosing between windows or linux, go to https://areweanticheatyet.com/ and https://protondb.com to see if there are any games you really want to play that don't work on linux(and mac too). Many games with kernel-level anti-cheat or new(DRM is removed after some time due to subscription costs for the publisher) AAA(A) games with aggressive DRM might not work, possibly even on VMs, with Mac included. For non-gaming software, check https://alternativeto.net/ for any linux alternative. If there are no decent linux alternatives, you can run windows apps through wine. I recommend GUI frontend like bottles or lutris, or you can just add it to steam as a non-steam game and run it through proton(You can run other steam games at the same time). Alternatively, winboats should run any windows software by using VMs(higher resource usage), and waydroid(slightly complicated to set up) should emulate most android apps.

If you want to use linux, then there are gaming distros like bazzite, cachyos or nobara. All of them should have everything required to play vidya preinstalled or easily available in package managers and should work with your specs. Most distros have tutorials, advice and help available on their wikis/docs, subreddits, forums and sometimes discord servers and there are plenty of youtube videos or blogs showcasing just about anything you might want to get running on linux. There is also an exhaustive list of distros on distrowatch if you are curious.
If you want to stay on windows, you can try to enroll your PC for ESU to get free updates until oct 2026 just by logging in with your microsoft account and syncing your PC settings. There is also commercial ESU program(support until oct 2028) and LTSC(support until jan 2027) and IOT LTSC(support until jan 2032) versions of win 10, but without putting on an eyepatch(haram on tftv), those are out of reach for non-commercial users. The spec requirements of win11 and even the account requirement can be bypassed, but that comes with uncertainty with Microsoft either breaking something or cracking down. Other than that, I recommend running TronScript(before running, bookmark your browser tabs or make backup of your browser profile in appdata) and debloating software like winutil or really anything from this list.
PS. You will need mastercomfig medium/low regardless of your choice, and Mac might offer better performance.

Tried multiple approaches on Mac, all disappointed:

• UTM - unplayable, hovers around 30 FPS (constant dips below, with masterconfig low)
  
• Whisky(no longer maintained) - wasn't able to install Steam
  
• Parralels - performs better but dips below 60FPS are common. (with masterconfig low)

I know for a fact my G3258 was able to maintain (with very rare exceptions) above 144FPS around 5 years ago, will try to revive that box when I get the time

Have you tried other similar software from that Reddit list. Reddit has obfuscated the rest of the post with the barely visible "Read more", so I'll link to the old version of Reddit: https://old.reddit.com/r/macgaming/comments/1k98zht/whisky_is_no_longer_maintained_now_what_a_guide/
Besides Whisky, there's also Crossover(paid), Sikarugir(formerly named Kegworks, in a post above I've linked to a yt vid of some guy installing the app and then steam and launching a game), Heroic launcher(It's also on Linux, and according to an issue on github you'll have to install steam manually) and Porting kit(Fork of some other project, not the apple one). But if you don't want to try those, it's understandable.

Tried this and performs the best so far, thanks! Ran timedemo benchmark1 and got 105 on Sikarugir vs 75 on Parralels

Might test out different engines and translation layers on Sikarugir

no idea how much of a pain it is but you could try installing fedora asahi linux, and running steam with fex or box86 and checking the performance. supposedly the gpu has a mesa driver so should be accelerated