The people doing the deliveries for e.g. Wolt earn at minimum of 120 DKK an hour (~18,5 USD) on a scheduled shift and can often earn more, depending on how much they are willing to work. The last average I read is around 150DKK an hour (~23,30 USD) for delivery personel in that company.
The main issue with unionizing in Denmark is that it would require the companies to sign the delivery people to fixed-hour contracts (think nine-to-five), which doesn't work with the business model and isn't what most of the delivery people have expressed their wants about. Most of them enjoy the freedom and many in creative industries (e.g. musicians) use it as a way to supplement their income.
I think it is important to recognize what unionization actually means and whether or not that solves the problem, and before that; figure out what the actual problem really is.