401k Rollover experiences?

HODLer since 2017, not a developer but a firm believer in the future of crypto.

I recently separated my employment and have a few $K in a 401k that I've been thinking about rolling into ETH (and maybe 20% BTC). I've heard of a 'self-directed 401k' but am curious about the level of effort/knowledge required to perform this rollover, and more importantly, the filings or other paperwork that would accompany it, whether now or at tax time.

Any tips, resources, or stories are greatly appreciated! I looked for a particular flair but didn't find the right one – plz let me know if this is misposted.