USDC [0] essentially can be used as a multi-chain stablecoin. You can accept USDC with other cryptocurrencies listed on [0]. Here's an example of a user paying with Solana USDC:

Depending on the fees, the merchant could use say, Solana Pay [1] or MoonPay [2] and the user on-ramp is the Phantom Wallet [2][3].

All of that addresses every single bullet point.

[0] https://www.circle.com/en/multichain-usdc

[1] https://solana.com/news/solana-pay-announcement

[2] https://www.moonpay.com/business/onramps

[3] https://www.moonpay.com/blog/moonpay-phantom

[4] https://phantom.app/

I appreciate the links.

I do not see the example link of user paying with Solana USDC?

In your links I did not see useful case studio OUTSIDE crypto space.

Your links show tons of crypto to crypto use cases. (currently emphasing being on various nft related services, like that phantom.app -> A beautiful home for all your NFTs).

I sell virtual products/services which are not related to crypto. I want to offer an ability for someone without any cryptocurrency to purchase these virtual goods from me.

So the chain could be https://www.moonpay.com/buy -> users uses some wallet -> payment widget on my site.(like old bitpay)

There have to be examples of a regular ecommerce shop having this functionality.

Again, I want Joe Sixpack with a CC but no crypto to come onto my site and pay with cryptocurrency in a user friendly manner.

I googled "merchants accepting moonpay" and could not find a list. Are you aware of one?

Edit: ditto for solana pay, it looks like this was announced this month an "will" do a lot of stuff but doesn't exist