Two versions:
It's only one or the other

Feats - Can be retaken, 2 each

Potions - All of them in tutorial chest, can  be summoned via tutorial chest mod

Unlimited resource options include:

Spell Slots 1 - 6

Warlock Spell Slots 1 - 5

Bardic Inspiration

Channel Divinity 

Channel Oath 

Fungal Infestation 

Lay on Hands 

Ki Points

Rage Charges

Sorcery Points

Wild Shape Charges

Superiority Dice

Replenishes whichever resource on your turn, when dealing damage or upon casting anything

You can have a single level spell slot and spam it forever (assuming you had the action points)