How do I /testfor more than 1 item in an inventory without a need to use the /scoreboard command? [duplicate]

You've got a couple syntax errors in the NBT portion of your /testfor command. The command, as you have it, should be /testfor @p[r=2] {Inventory:[{id:minecraft:gold_nugget}]}

However, unless you literally only want to do something to the world whenever there is a player within 2 blocks with a gold nugget in their inventory, you are not going to be able to do anything with this testfor command. testfor does not allow you to pass player information to any other commands. You can see if that player exists, great, but you can't do anything to that player. If you want to do anything to that particular player, you will absolutely need to use a scoreboard. I don't care if you don't want to learn it, that's your only choice (if you just want to do something simple like summon a TNT at a particular location, then you can continue on your merry way with your testfor I guess).

If you do these setup commands:

/scoreboard objectives add items dummy

/stats entity @a set AffectedItems @p items

/scoreboard players set @a items 0

Then run this command: (N.B. The execute is ESSENTIAL)

/execute @a ~ ~ ~ /clear @p minecraft:gold_ingot 0

This will then mean that each player has the number of gold ingots in their inventory as their items score.