I put Linux in my old 2017 MBA, almost everything feels like its running at sub-optimal speeds

If it is the older MBAir without USB-C ports then Linux should run fine on it although I've never actually used Linux on it (I have used Linux on 2015 MBPros).

PopOS is a new distribution created by a computer manufacturer by modifying Ubuntu. I used Ubuntu and its various flavors many years ago and discovered Ubuntu can be a giant mess and have performance issues (especially with any of the other flavors since they are not as well tested). Plus the default Ubuntu requires a system with lots of resources. I've never used PopOS so I don't know anything more about it.

I would suggest trying Linux Mint instead. Linux Mint is also based on Ubuntu. I know a co-worker has installed Linux Mint onto some of our organization's older Macs to hand out to the less fortunate. This co-worker has never had any issues installing Linux Mint and is not really a Linux user.

I personally go with Debian on my systems for multiple reasons (Ubuntu is based on Debian). The software is much closer to the app developers' intent and it seems much more smooth, but Debian does require a lot more work to setup & configure.....however, once installed & configured, it is no different than any other Linux distribution. Debian stable is on about a two year release cycle on average these days which is fine for most purposes, although if you need the most recent GPU drivers, then that could be a problem since Mesa is difficult & time consuming to recompile.

If you are trying to give this laptop "a new coat of paint", I'm assuming that perhaps the macOS performance may not have been so great either? If so, that may indicate some sort of hardware issue.

Also, these MBAirs are not very fast systems so they will show their age much more quickly than a MBPro. I also find these MBAirs tend to develop some hardware issues over time although I cannot be sure if it is due to age or whether it is from abusive users since most of my organization's MBAirs are being used by people who are quite abusive & uncaring about their laptops.

Edit: I'm not sure gaming is much of an option for a MBAir since it has very low hardware resources (slow CPU, basic Intel GPU, and I believe the 2017 model has 8GB which isn't much for gaming).

Also, if this is a 2018-2020 Intel MBAir with USB-C ports, then forget Linux since the hardware is not well supported on Linux. Drivers don't exist for half the hardware features, although I did just read a news article that the Asahi Linux team is actually sending in a Linux kernel patch to provide Device Tree information for the T2 chip for some 2016-2020 Intel Macs so this may be starting to change a bit, but it will be some years before it would even be supported.

If it were me, I would take KiltedTim's suggestion to reload macOS High Sierra on this Mac. Then you can create multiple Linux boot drives to "try out" various Linux "flavors" to see which may work best with your Mac, before committing to any one version.

Personally, I haven't tried using Linux on any of my old Macs by placing it on the Mac's internal drive. I did; however, did so on some older Windows PCs that were stuck at Microsoft XP and made them "useful" again.

I’m not sure what you expect from this community.

Apple doesn’t support any variation of Linux running on Apple hardware.

You’ll have much better luck posting in a forum dedicated to whatever flavor of Linux you’re trying to run.

You could, of course, revert to running High Sierra, but as you’re well aware, that is obsolete and no longer supported.