We live on internet everytime, if you are on crypto world, better to have not just one device but separate it which one you have daily use for internet and which one you can use itu for wallet.
This is one of the better moves to avoid our important data being stolen through malware infection. Aside from this, if one is limited on resources,
one can just create a virtual system by creating a virtual machine inside his pc and using that to browse. Of course, one should also be careful not to fall for phishing sites since virtual machines can't protect us from the error of filling important details of our account on the phishing website.
I am on over 5 years use non custody wallet, so far don't have problem, because I used the methods.
Yeah, your stated method is one best way to protect our important data from malware that sniff and steal our data without our consent. But this can't protect us if we fall victim to phishing sites since it is a personal error (giving out important information thinking that we are on a legit site) that give the creator of the phishing site the opportunity to steal our important information specifically our financial accounts and wallet seed phrases and private key.