I'd recommend not taking any security advice from internet forums at all if millions are on the line, regardless of OS. I'd hire a professional to harden the computer I want to use for that and wouldn't use it for anything else. An apple device would probably be my go-to there over any Linux system.
I'm not a VIP, but I have some huge huge huge secrets that are worth at least a million dollars, maybe 10s of millions of dollars, that I need to access with a computer.
Malware means potentially losing millions or tens of millions of dollars. I'm so afraid of those secrets, I don't even access them on my windows computers unless necessary.
I'd love to be comfortable doing this, but given anyone can seemingly make a python keylogger, I'm not really comfortable using my computer(windows or linux) for this purpose. Gaming/updating my website/etc... all of that, who cares if I'm hacked, I got backups. I just havent found a great way to keep secrets that need to go online.