How many enchantments can you stack using an anvil in Minecraft?

I have been wondering for a while, can I enchant two of my pickaxes and then use an anvil to create a new pickaxe with two different enchantments. If so, can I stack more than two different enchantments such as combining a pickaxe with efficency I and a pickaxe with fortune II and unbreaking I?

You can in theory add every enchantment that is compatible with a tool/weapon/armor onto the same item.

The bow can have these 7 enchantments, though mending and infinity are mutually exclusive. So you can have up to 6 different enchantments on a bow using an anvil.

There are some limitations though, as merging enchantments is more expensive when you try to add many at once, and there is a penalty for enchanting the exact same tool multiple times.

You can only do this until the cost is 40, or higher, so you may not be able to add all possible enchantments for a single item onto it.

You can go beyond that limit in creative mode.

I did research, and found that you can put two items in an anvil that are enchanted, then get a tool with all of those enchantments (enchantments of the two items).

https://minecraft.gamepedia.com/Anvil_mechanics