[Feature Request / Bug] Allow adding tx keys to view-only wallets.

[benhall847]

Personally I'd love an option to be able to track my hardware wallet via a view-only wallet on cake wallet.

" If your wallet has outgoing transactions, the balance displayed will not be correct. To get a correct balance in a view-only wallet, you have to import the accompanying key images of each output of the wallet." - getmonero .org/resources/user-guides/view_only.html

Cake Wallet "supports" view-only wallets

Yet it doesnt fully support it.

As far as I can tell - there's absolutely no way to import tx keys into the view-only wallet.

Therefore - as soon as the wallet being viewed sends a transaction - the balance is displayed incorrectly on the view-only wallet.

Mobile wallets are the most practical view-only wallet. I feel like a desktop view-only wallet sort of defeats the purpose for an individual. (unless its a business owner etc..)

It seems currently only the Monero GUI/CLI fully supports view-only wallets.

(Note - I'm assuming a 'tx key image' is the same thing as a 'tx key' - please correct me if I'm wrong.)

Steps To Reproduce -

1. Create a new wallet & send it 5 cents of XMR.

2. Restore the wallet as a 'view-only' wallet on another device via cake wallet / monero.com wallet (use the primary address + private view key + restore date)

3. Send the 5 cents of XMR to another wallet.

4. The 'view-only' wallet balance is incorrect.

Expected result - User should be able to add to the view-only wallet - the tx key of the incoming transaction (5 cents incoming) This would allow the 'view-only' wallet balance to be displayed correctly when the output is spent.