I use Adobe Illustrator daily at a very high level and have about 25y of source files in its private format, as well as a bunch of plugins I rely on. How well can Linux deal with running a version of it written in this decade?
Inkscape is not an option, nor is anything involving importing PDF/SVG, those have to expand a huge ton of stuff that's represented much more compactly in an .AI file. It's about as large a difference as that between an executable file and its source code.
I don't think there is an answer. The best you can do is probably running Windows in a VM and limiting its use to applications that you really cannot replace. It's been a while since I used a VM on Linux, but VMware had a thing called Unity Mode where you can have application windows from the VM on your Linux desktop:
https://techdocs.broadcom.com/us/en/vmware-cis/desktop-hyper...
It seems like they removed it from VMware 17.6, but maybe another VMM still has this functionality?
I haven't tried it but I've seen this project promoted in some tweets and maybe even here: https://github.com/winapps-org/winapps
https://www.vectorpea.com/ and https://www.photopea.com/ are the lowest barrier to useable alternatives. You can even save them offline and convert to PWA, with very little friction. vectorpea and photopea should handle your .ai files admirably.
Inkscape, Affinity, other open source alternatives exist, but have a remarkably different UI and don't capitalize on your muscle memory.
The feature overlap is bordering on complete, but there are some Adobe Illustrator only perks, for sure. Most of it you can make up for with any of the frontier image AI models.
There are plugins - if you're well versed in how they work, converting between AI and vectorpea should also be a piece of cake with AI.