Did a quick search for this question in this community and didn't find it already, so: is there a native way (yes, I know of and use uBlock Origin, and just added these blurbs to my uBlock) to turn off the New communities and Active communities blurbs in the right rail?

Not currently, but I can add some extra html that will let you target them with custom CSS that you paste into a field in your settings. This will be in the next version of PieFed, released this coming week.

Thank you so much!!! This will help a lot when I use Piefed on mobile, no uBlock to speak of.

For people reading this later, the CSS I put in to block these things was

#new_communities_card, #active_communities_card {
display: none;
}