Revise `External signers` page in `How it works` section

[GBKS]

This has been brought up a few times. It could cover topics like...

• Use cases
• Hardware wallet UI design considerations
• Interaction between hardware and software wallets
• Features
• Popular products and product categories

The "Hardware" overview page has a short section about hardware wallets. This new page would be a natural extension of that content, but could also be linked to from relevant content in other sections (like private key management and transactions).

[GBKS]

Idea to add recommendations for users on how to handle hardware wallets by @moneyball (original comment).

Additionally could provide guidance on locations to store hardware wallets and associated tradeoffs (eg same or dispersed geographic location, bank safe deposit box vs. personal safe, etc.). (this should also wind up in the design guide)

[Bosch-0]

Revisiting this discussion.

My suggestion is to have this as a separate product section in the guide that goes into detail about all the different ways in which a HWW can be designed. The focus being on the UI components not the hardware design ofc.

Relates to Moneyball's comment here

If there is a desire by the design community to also assist designers and developers to build products for power users and LN router managers, this is where I'd suggest a separate section is created in isolation to help with those important but niche use cases. This is where detailed channel management could be covered.

[pavlenex]

Just a note, this page can be the connector for our collab with the real-world projects, in this case, Square, which is now def working on a hardware wallet.

[Bosch-0]

This could be another "mega case study" section we include in the guide.

[Bosch-0]

Just picking this up again, when we have the Daily Spending Wallet section mostly fleshed out, we should start working on a 'Savings wallet' that covers this and has a more on-chain focus.

Maybe change this issue to Create a Savings Wallet section in the guide.

[GBKS]

I'd start with a very basic page for people who know little to nothing about hardware wallets. Then we could build on that.

[Bosch-0]

Let's start with making an External signers page in the How it works section. When we eventually get around to fleshing out the Savings wallet reference design we should dive deeper into this topic.

[Bosch-0]

We already have one actually, we should expand on that section https://bitcoin.design/guide/how-it-works/private-key-management/external-signers/

Need to add new content around NFC privacy considerations #580