|Beware of the fees though, which are typically higher than a traditional IRA.|
Not unless "traditional" means a company managed 401k versus self-directed which you manage yourself. Managed usually only have a few ETFs or the company stock. When I retired, I moved everything to a self-directed IRA. The choices (stocks, bonds, ETFs, etc) and fees (low or none) are just like a taxable brokerage account. eTrade does not offer individual cryptos, only ETFs like GBTC, ETHE, etc.
So i really don't know what they mean. I'm not aware of any brokers who offer cryptos directly but I think that will come in time.