Thank you chip!
I think that plot is the most useful piece of information I have come across! I now understand your point about LDO vs buck-boost, the buck-boost will only operate ever as a step-down regulator anyway, so its not worth it.
If it is not too much to ask, could you also comment on the necessity of a mosfet to disconnect the battery from the load while charging? I’ve seen most designs don’t include this, so I am not sure if it is overkill or if it is worth the effort.