How to check for minimum amount of items in Player Inventory?

For starters I am aware that a similar thread already exists, however it does not answer my question as well as being outdated.
Reference: Testing for a minimum amount of items in a players inventory

I require a single command that can check if a player has a minimum amount of x item in his/her inventory.
Format: /execute if _________________ run _________

This is for the CommandPanel Plugin, and is supposed to make an item buyable, however if there are any other suggestions on how to make an item buyable with CommandPanel Plugin TELL ME please!

https://www.spigotmc.org/resources/command-panels-custom-guis.67788/