CoinRequest request button, next to the Metamask option

**What problem are you trying to solve?**
The MetaMask request functionality: https://metamask.app.link/send/0xd3C64Ec55d736b1eB5A774348e6511C8Bd4B38E1@1?value=8e15

Is nice, but bound to Metamask alone. EIP681 (ethereum:) isn't useful either in most cases since users tend to have multiple wallets, and the correct method (android pop-up to choose your wallet) is not functioning on other devices.

So if I would like to pay with wallet A, but wallet B is the latest updated etc. , the ethereum: request won't work.

We're building a cross-platform, cross-wallet & cross-namesolution payment/requesting service we would like to introduce next to the Metamask invoicing method, so users can request/pay with the wallet they prefer.

**Describe the solution you'd like**
With the CoinRequest method (coinrequest.io) you can send the request to whomever you like, and pay with over 50+ supported wallets and counting.

Transfers are non-custodial, and go directly from you to the recipient. It's free for wallets that implement it and we support name services so users can request and pay even easier.

https://twitter.com/CoinRequest/status/1167403944060030976?s=20
DigiByte request example

https://twitter.com/CoinRequest/status/1169971860727050242?s=20
Ela pay example

**Benefit of adding to the Metamask wallets**

1) Users can share where they want, with whom they want
2) Users can pay with Metamask, or one of the 50+ supported wallets
3) Free to use, increasing the UX by allowing people to choose with what they want to pay.
4) if Metamask not installed, there will be a pop-up linking to the download page

The issue mentions no files, tests, or entry points. Start by locating the existing MetaMask invoicing method and determine how a CoinRequest option could support the described cross-wallet flow; done would mean the requested payment method is available alongside MetaMask with the stated wallet-selection behavior.

Written by the indexing model from the issue text.