How about if you build your own airgapped hw wallet? There should be plenty folks here who would be capable of doing so. (Doesn't even have to be the most hardened and audited implementation ever since you won't release this to anybody.) This makes you vulnerable to purely very targetted attacks.

As long as the cost of sucha single-target attack isn't substantially below its potential upside, you should be safe.

Otoh, it's only meaningful if you have more than just toy assets in there.

There should be a range between those two though that would contain lots of folks comfortably.