I think this GameBoy solution (links courtesy of @rich) is futureproof and is highly resilient because you can’t trust existing and future supply chains:
I believe many extrinsic signing UIs across all of Web3 can be mapped into GameBoy interfaces and can be done in an entirely open source way, with L1s/L2s+Substrate parathreads collaborating for a super decentralized resilient development path. Instead of the dependence on Ledger, we depend on an ancient technology stack:
(a) unlike Ledgers now and in the future, provably WITHOUT backdoor possibilities because people from the past could not have known about the future
(b) unlike Ledgers now, has a programmable low cost ($100) display that can display L1/L2 complexity with just a little bit of metadata
A proof of concept of Web3 GameBoy (or some such ancient device) signing a Substrate extrinsic or EVM Transaction would involve getting sufficient Substrate runtime metadata + EVM address ABI to be rendered on the ancient device. I think a good UI would prevent a lot of stupid things from happening, like getting the decimals right and mapping activity into the users USD/EUR/… native currency.
Can all of you remaining Ledger fans attack this GameBoy style of solution?