Some time ago I considered one of the Accusump or equivalent of the other brand. However I found it much easier, useful, and convenient to just use an electric pump (tilton differential oil pump) plumbed with a weld-in AN fitting for input and a line to oil filter housing for output.
Much less room to find too (those accumulator designs can be quite large!). I also think those storage type are very limited and would only be good for a fraction of oiling backup. I also have my doubts about them possibly holding a full pressure charge over a long period.
With this pump system I can easily hit the manual switch before startup and oil as much as I want before startup. Other uses also possible but not ones that I need. Such as engage the pump if you want when oil pressure is at x psi or any other parameter desired.
For me it is the way to go to address pre-oiling.
I think this is the one I use