Better have a device in agnostic mode, e.g. a Pinephone or Librem 5 or privacy phone with kill switches which can read slate-packs as QR sign them and show return slate as QR. Better to never have the seed leave the secure offline device/hardware-wallet. Problem is that they are expensive (500$ for Librem 5 or Privacy phone or 200$ for Pinephone or 399 for Pinephone (pro)).
The best would probably be the Pine phone (pro) since it supports many linux OS. I do not have one but I am fairly certain I could compile the grin rust wallet or grin++ client to run on it, so it can be used as sort of hardware wallet, but it does lack a secure element.
The development cost of this would be 0$ 