Yes it is, Theres a whole function for it for example,
local productId = --Item ID
game.Players.PlayerAdded:Connect(function(player)
Game:GetService("MarketplaceService"):PromptProductPurchase(player, productId)
end)
But this is meant for me to sell my own items that I make in the game. is there a way to link it up with the Roblox Avatar Shop items and allow players to use them in my game?
local productId =11419319 --Item ID
game.Players.PlayerAdded:Connect(function(player)
game:GetService("MarketplaceService"):PromptProductPurchase(player, productId)
end)
You cannot prompt purchases of items that are on the website > catalog and are made by someone else (i think you can prompt purchases for clothing that you made). You can only prompt purchases for in-game developer products.