Game Start allows you to give items to players the first time they join a world. It also allows for custom welcome messages.
To use Game Start, open the config file titled gamestart.json in your config folder. You can change the loot table given to players when they first join here, and also set a custom message to display in chat. Use the phrase "&*" in the config to print the player's username.
Game Start is for Fabric 1.14.1 and requires Fabric API/Fabric Loader to run. Game Start is in alpha, and will most likely have breaking changes in the next coming days.
Game Start is licensed under MIT; do what you want with it. Yes, you can use it in a mod pack.