At a bare minimum make sure you check and adjust the pH, but yes it can be done.

The main issue is that the water in the dehumidifier is a potential carrier of anything that was in the air at your home. Just be mindful that you aren’t creating a transport mechanism for mold or bacterial spores and your plants won’t mind.

If you’re concerned about it the water can be used for ornamental plants rather than edible ones.

You could also mix some soap or detergent in it and wash something, like your car or the dishes or whatever. That way it doesn’t matter about the pH or the bacteria.

I successfully used it for carnivorous plants (which require rain or distilled water, because they don’t like minerals, which often are in tap/ground water)

Depending on how your dehumidifier works you can use it for many things.

If it’s chemically operated the water is going to be full of whatever hygroscopic salt is being consumed so maybe just for washing clothes/dishes

If it’s the standard refridgeration based type then it is essentially collecting distilled water from the air. However that water is then left to stand on the cooling surface/in the resovfrenchnoiseswhocanspelltheirwords.

It might have collected some dust, mold, or algae. It could have also trapped any contaminatants from the air in your home as air was cycled past the wet elements.

I would not drink or cook with it, but unless you are operating it next to a source of harmful pollutants like say a 3d printer, stove, fireplace, or a very moldy laundry it is going to be fine for washing and watering.