I've never known gravy to be poured over liver at the table - liver and onions are cooked in gravy, though I use flour and a dash of Marmite rather than gravy-browning, and (if available) a cheap can of ale rather than water.
i don't pour gravy over food at the table, I do it while serving up when there are only the two of us. Obviously I would put gravy in a gravy boat if we have guests.
My liver and bacon does not include onions. I buy chunks of liver because that's the way they sell it in the butchers here in NZ and I slice it quite thickly.
I coat it in flour (no seasoning) and fry it in oil, the bacon goes into the same pan.
The gravy is made separately which I pour onto the man's serving. I usually do mashed potatoes and occasionally will pour a smidgeon of gravy onto my serving of that, otherwise I have HP sauce. Thus, avoiding soggy bacon.
Crispy bacon is my own choice because I do not like the fat half cooked. I have never heard of it being an American influence.
And, quite often we will have Brussel Sprouts with our liver and bacon.
I cut the bottom off the sprout, remove the outer leaves, cut a cross through the bottom and boil them, without salt.
My grandmother, who died in 1968, taught me how to prepare and cook fresh veg when I stayed with her during school holidays. Granddad had an allotment, I would accompany him to the picking of veg for 'tea' then help to prepare whatever it was.
Tea is in inverted commas because that's what the evening meal was called in those days. These days I call it dinner.