I cannot come up with a filler like Duraseal etc ( minimum I can
find is 5 gals) in my area and
My time is running out. The floor I have to start needs a trowelable filler.

I have seen the pros make it up out of sanding dust and what I always thought
was urethane but I haven't been able to find any comment on this, online.
Some have suggested white glue and dust but that sounds like a sticky mess.

Is is possible to use a mixture of dust and either a water based or oil based
urethane as a trowelable filler?

you can mix fine edger dust and lacquer sealer into a slurry and trowel it out with a flat drywall knife. its flammable so you have to have ventilation and NO OPEN FLAMES, including the pilot lights on stoves water heaters fireplaces ect. Its not dangerous if you are careful just keep the windows open with a fan blowing out that will help move fresh air in so you dont get lightheaded.

you can also buy online, google "woodwise wood filler"or dura seal wood filler lots ship same day!

Thanks Kevin.....by lacquer 'sealer' I assume you mean a clear lacquer like Watco
which is available in my local lumber store.

Clear Watco works great

Can I stain a floor after using this trowelable filler(sawdust and clear lacquer)?

We use Sheetrock drywall compound. White bucket with the green top. We mix it with water to give it the consistency of pancake batter and then tint it to match whatever floor we're using it on.