I want to complete the dex and get the shiny charm, however, I need more poké-dollars to buy more items such as pokéballs. Is there a way I can get 1,000,000 poké-dollars like in previous games?
I'm aware this question is old, but here are a few more ways:
Amulet Coin / Luck Incense. Try rematching the Wyndon Cup again and again. Your money totals will grow exponentially.
Gigantamax Meowth. Meowth's signature move, G-Max Gold Rush, scattters coins upon the field. Challenge the Wyndon Cup to gain vast amounts of money. Make Meowth hold an Amulet Coin or Luck Incense to further boost production.
Use the Digging Duo. While this does cost Watts, it's extraordinarily cheap to have them dig. They can find a variety of items to be sold, like Pearls, Nuggets, and Rare Bones.
Sell Fancy Apples. These curry ingredients are quite common, and sell for around 7k Pokedollars each. Other ingredients, such as Pungent Roots and Leeks, can also be sold.
Find Pearls on the shores in the Wild Area. While they don't sell for much, you can pick up enough to make it worth your troubles.
Participate in Max Raid Battles. They give out items like Nuggets and Big Nuggets, both of which can be sold for a tidy profit. A lot of the TRs Max Raid Pokemon drop can go for quite a bit, and they're easy to get.
Have someone trade you valuable items. If someone's nice enough, they can give you items like Pearl Strings that you can sell.
There are almost certainly others, but these seem to be fairly easy. Hope I helped!
if you go to the wild area and do 10-15 max raid battles and buy as many luxury balls as you can, you can sell them to the Pokemon center for more money. also farm for items in the wild area and sell them. you may find the digging duo as a help for this.