For being a carpenter myself, I'm actually pretty naive on the pros and cons and options of finishes for hardwood flooring.

I'll try to brief my situation and criteria:
I've built a house out of materials salvaged from a dismantled farmhouse. The entire house is old wood floor. My wife and I specifically avoided drum sanding the flooring once installed, because we didn't want to remove all of the age marks from the surface. I skated over the surface pretty well with a rotary style sander that floats on a foam pad, which for us did a pretty good balance of knocking superficial crud off while leaving most of the aged color. The floor has already been stained with Minwax.
Clearly a flawless appearance is not the number one priority.

I come out the gate with a resistance to polyurethane, because 1. we are going to have a house full of active lively children and I don't want to have to think twice about scratch damage, 2. we don't want any sheen other than perhaps a subtly saturated look, and 3. my mind revolts against the idea that I'm living on top of a layer of plastic instead of actual wood.

The thing is, polyurethane is mostly what I've been around, and I don't know much about the more old-fashioned options. My two main concerns are 1. how much water exposure does it take to start marring a non-poly finish (muddy boots, mopping, spills cleaned up within a minute or two...), and 2. how well does a non-poly finish harden, in terms of locking down splinters?
Being a salvaged floor, there are definitely a few concave rough spots that a sander can't easily get out... I just want socks to be able to glide around without fear.
My wife is concerned about the floor turning milky every time water gets on it, or getting water stain splotches everywhere.

I only just encountered the term hardwax oil today... it sounds like a promising product, but am I seeing right that it costs $250-$300 per gallon?
Does anyone know anything about making a homemade blend of linseed and beeswax, or something along those lines?
Wax alone gets milky when wet, right?
Linseed alone probably wouldn't lock splinters down very well?
Any other suggestions from the gurus that would fit the criteria we're looking for?

Thanks a lot!

As an additional consideration, does anyone know what hardeners are added to storebought hardwax oil that a person might be able to add to a homemade mixture of oil and wax?

An oil finish can build up to a nice film, similar to a varnished floor. An oil finish like tung oil will hold up to normal traffic and will be easy to add to the film thickness at any time there is wear. I just renewed a 20 year old "pure" tung oil finished floor that was worn in a couple areas in the kitchen with little trouble. Cleaning with detergent and water and a red pad under the buffer got the floor clean without any "white" areas. The worn spots were re-sealed with a seal coat of Waterlux, then after drying a couple more coats of Waterlux tung oil finish was applied to build up a film type finish that is smooth and easy to clean.
I do not think much for the one coat seal and finish products and would never recommend these for a kitchen. Waterlux is sold in quarts of both seal and finish. I recommend satin for the final coat.

Thanks for the suggestion. Waterlox looks like a good candidate! I'll gather a little more information but we may very well go with that...

I've ordered Waterlox: going with the Universal sealer followed by the H20Lox Matte topcoat. We'll see how it goes!

Oh dang, sorry I'm late to the party.

Try this hardwax oil if you can. https://www.rubiomonocoatusa.com/

Hi Stephen, no worries.
I did see Rubio, but I wasn't sure how far the coverage went and it looked extremely expensive to coat an entire house full of wood floors. Maybe I'm wrong and the coverage is very good.
I applied Waterlox (UTOS followed by H20Lox Matte) and I think I'm going to be happy with it. It has somewhat of a flexible shielding layer which I think will be helpful for our old rough wood (but hopefully remaining spot-repairable).
Thanks for your input!