I migrated by sitting in all and using the Subscribe and Block options. Eventually my subscribed view was showing me items of interest and I was spending a lot less time in All.
This is the way. Don't be scared to block communities or even users that posts content you're not interested in. Eventually you will have curated your feed
I don't know but let me know if you find a Bogleheads.
And I'm sure you know already but you can block out all the bullshit political and tankie instances with a couple of clicks! No more sifting through the muck if you're an 'All' scroller.