The Solo 401k is an incredible tool that allows for diversified investments. Within your plan, you could open a trust checking account, a brokerage account, and/or a cryptocurrency exchange account. Once your funds are in an account, you can then invest in almost anything.
The Solo 401k is completely self-directed, so you have the power to invest in what you want, when you want. This includes moving money around inside of your Solo 401k. You can move funds from a brokerage account to a bank account, and then wire those funds to the closing table for a real estate deal without any tax implications.
Because your funds are staying within your Solo 401k, no taxable distributions are occurring. You can move funds around your Solo 401k as many times as you want as you are the plan custodian. As long as you are using retirement funds, and the investment is not prohibited by the IRS, there will not be any tax repercussions.
If you ever have any specific questions about investments or taxable distributions, we recommend consulting your tax professional and/or attorney.