I also have a 20"/406 wheel bifold in steel, chrome-moly steel so bare new it was supposed to be 28 lbs with fenders and a small steel rear rack. About 1.5 lbs lighter for aluminum frames with aluminum rear rack by same company. Cheap "hi-ten"(sile) steel bifolds can easily add on 10 lbs for very similar bike, but I can't recall if those had steel seatpost/handlepost/handlebars/rims, I just remember the weight spec of 38 lbs.

Right now, 28 lbs would be feather light, as all the additions on my bifold put it well over 50 lbs; 2X crank and front derailleur and shifter, bolt-on aero handlebar, stout rear rack, trunk bag full of tools and spares, full-size rear panniers, small front rack and panniers. But for utility as a townie, it's awesome, I can do big food shopping. But the carry up stairs is a grunt.