adding item on Shopping Card and pay using bitcoin
yes, this is possible with BTCPay. It has integrations with popular e-commerce solutions like WooCommerce, Shopify, Prestashop. Here's a tutorial how to get setup with WooCommerce:
https://youtu.be/ULcocDKZ1Mw?si=a3kTStPNvsrFskpw do I need to have a BTCpay server of my own?
No, you can use a third-party BTCPay instance securely by using a read-only API-key from your Blink dashboard. You can find a BTCPay Server in the community chats or in this directory of public third-party instances:
https://directory.btcpayserver.org/filter/hostsAre you officially representing the blink plugin?
The plugin was developed by MrKukks upon a bounty I created, so I was involved in the plugin's creation.