Regardless of you plugging in a hardware wallet into your computer ^{[specifically referring to your second PC]} or not, there's still no guarantee that it's going to be or remain 100% ^{[or close to a hundred]} safe.
^{- IMO, your best bet is to go with @bitmover's suggestion and use a hardware wallet like Trezor instead.}

IIRC, for the Trezor Model T, it's 12 words by default ^{[128 bits]}.