There is no reason why you can't resume apical growth. It looks to be recovering as is. It is difficult to tell, but the pinkish growth is new, yes? That is what will resume growing as your "main trunk".

You can see the angled swelling above the node, that is the branch collar you need to every so slightly cut at, or minutely above. This is where the callous wood will form to compartmentalise the wound. As the stub you have cut is so long, the tree will will have to wait for the stub to die and drop off before closing.

First step is prune at the collar "target". Then you will let tree recover for a while and dictate what new growth will resume the vertical trunk that you want. You will then select and encourage that growth to resume being the main trunk. You won't be pruning anything for a while after your first cut, you need the tree to recover. Most pruning events are annual and never more than 25% of total canopy loss. Note on pic, zoom in.

I don't know what the other commentators mean with their comments, this is fairly standard arboricultural pruning practices. If anything they said was true, any tree other than a mature conifer that suffered minor "topping" damage in the wild would be an instant death sentence for the tree. This is not the case in a majority of situations.

For a real world example, here is a tree that was topped by a moth and the pruning that I did to recover it. I pruned some of the new branches at the wound to encourage the upper growth. There are notes on pic, you need to zoom in,

Edit: Just went to neighbours house and they have a roughly pollarded Avocado. You can see the multiple regrowth points, you would select one of these to be the new trunk. Just a good demonstration of the same species getting on with it.

If you cut the top off then it will only be able to grow branches at this point.

Pinching' describes a type of pruning that encourages plants to branch out along the stem to become fuller and more bushy. When you pinch out a plant, you remove the top of the main stem, forcing the plant to grow two new stems from the leaf nodes below the pinch.

Subsequently, you can try grafting but you need some healthy plant to take from if your going for aesthetics.

Let it heal though before doing anything. I feel thing thing needs leaves for energy

You could try grafting it. It’s been a while since I last grew avocado plants, but I would graft them, especially because it will help them produce fruits later on.

They are easy to grow. Just toss another seed in the dirt beside it.