I use a bitkey for my mum but always worry over the upper limit that can be 'secured.' What's the upper limit, nostr:npub1qny3tkh0acurzla8x3zy4nhrjz5zd8l9sy9jys09umwng00manysew95gx et al or there isn't one as long as the tradeoffs are accepted.

I'm not too concerned about it not screen having a screen as we do regular rather large lump sum buys.