For the Follow mode, Olivero provides a perfect region (rotated 90 degrees) where it already places the RSS feed icon, but if you try placing the RRSSB Block you will get either too long buttons (going outside of the container div) or, if you try setting a custom size (keeping maximum rows = 1) you will either get wrong size of icons or they will disappear completely!
Active
2.5
Miscellaneous
Thanks for the report. It seems that the key point is the rotated region - it could be any theme. It's not something that's currently supported, however it's an interesting idea. I guess the solution is most likely in the RRSSB+ library which provides the JS.