Strictly speaking, both Mint and Bazzite are as customizable as the other. It’s just harder on Bazzite because the “obvious routes” are disabled for safety. Flatpak is available on Mint as well - it’s universal, and most distro enables it by default except for Ubuntu and more “minimalist” distro. Also, Bazzite only have KDE (SteamOS’ desktop mode) and GNOME (default for most Linux distro) supported, no Cinnamon support unless you DIY it (not recommended, not official supported).
As for Win11, that’s tough to say. It depends on what aspect, and I’d recommend looking up videos on YouTube for this.
As far as work and productivity goes? Windows 11 is still better, hands down. Unless you’ve done the hard work of re-learning your workflow and issue resolution, Windows will always be better. If you have optimized your workflow, then Linux is definitely better. For me it’s definitely better even with the annoyance WPS Office has over MS Office, but I do need Windows (via VM, remote, or dualboot) for my VBA and macro files. But for most of my tasks, there’s no beating KDE with fully set up windowing rules and panels for my workflow and sensibilities. Windows 11 isn’t THAT bad once I debloated it and use Windhawk to modify some stuff, but it’s still way more annoying than just using KDE.
For gaming, check ProtonDB and areweanticheatyet as usual. Steam Game Mode is MILES ahead of Armory Crate. Same goes for Heroic vs GOG/Epic Store, to the point I use it on Windows as well. I don’t know about the specifics of performance and such (I’d recommend just using CachyOS if you’re going to chase that unicorn) but it works fine for me as a lower-end gamer. What’s important is that for the most part, there’s way less annoyances gaming on Bazzite than on Windows 11. No nagging, no weird update issues, battery life make sense, sleep and wake works properly like I’d expect a handheld does (though I don’t know if that applies to your GPU).
The main issue has been when you go off the well trodden path of Steam. I’m sure you’re already aware of the general issues if you’ve used Mint. But for me specifically, it’s quite annoying how Cheat Engine works less well on Linux (no lua script support), modding some stuff can be annoying, some anti-tamper and anti-anti-tamper naturally don’t work (if you play those multiplayer games or “alternatively-acquired” games), some Windows 11 tools has much less powerful equivalent (lossless scaling is still being worked on, Playnite is still being worked on, Wallpaper Engine can’t use its most powerful features, Cheat Engine has some issues as I said, some patches and tools are a PITA to get working if they work at all).
It’s not perfect, but in general the seamlessness of just pressing power button and gaming immediately is (for now) unbeatable. Ofc this is talking about MY experience running Bazzite on laptop and handheld, YMMV. A lot of it is also isn’t necessarily Bazzite specific, it’s just for a long time I had enjoyed Bazzite’s defaults over the others.