Van Eck Bitcoin ETF

Hello everybody! Happy holiday weekend (in the USA). I wanted significant exposure to Bitcoin. I have cold wallets and know how to use them, but I wanted to purchase using after tax Roth money to avoid tax exposure. So, I bought $500k of the Van Eck Bitcoin ETF using my Roth 401k account. It was an impulse buy and I didn’t study any of the other bitcoin ETFs. For those of you who have, is there much of a difference?

Also, has anyone ran into problems buying shares of a bitcoin ETF using self-directed traditional 401k account?

Thanks for any insights!