Use a secure non-Windows OS
Any OS can be insecure and have the potential to compromise your wallet file. It all depends on the user. You can be using OpenBSD but have a password called love123.
this is true. it is also not necessary to use a non-windows os to create your "savings" wallet. so long as the install is known to be malware free during creation, and you do not use but rather back up this wallet, you're good.
reformat windows, make wallet, backup and encrypt then delete original: gold. ONLY access said wallet from a known non-malware OS.