One of the top rules of computer security is: Don't role your own
Don't try and come up with some super smart, custom made, super stealthy way to "totally outsmart everyone" with. You will screw it up. You will forget your passwords. It won't work how you think it will. It will have huge security holes in it. No one else will be able to help you fix it. It will end badly.
This is particularly pertinent when it comes to full computers with full operating systems. They have huge attack surface areas, even when off line.
Instead, use the heavily battle tested industry standard of a Hardware Wallet and a well respected software wallet like Sparrow Wallet and ensure it's fully backed by your own Full Bitcoin Node.
We'd also point out that Trezor isn't that great either (although their Safe 3 is a step up). There are far better options and you can view, filter/sort and compare all hardware wallet options here. Tap the "i" button to see full specs and ratings. Our top rated ones are the BitBox02 and Foundation Passport.
For other specific reading try these :
Finally, welcome to saving your time and energy in Bitcoin. You won't be disappointment 🙂