Itch is a store. If you buy here, by whatever means and with whatever currency, wallet system, imaginary Itch-Coins or whatever, taxes are due.
They are due if someone buys your game and they are due when you buy assets.
So you would still need to complete a tax interview, before you can pay with your Itch-points. No matter if you pay out to yourself, or buy things on Itch again. What you would save however, is transaction fees from payment providers.
There might be some games where you can buy in, and shift ingame currency around between players. I guess those circumvent the tax issue, because you can not pay out. The games where you can pay out however, that's taxable income and might get complicated.