Yup, Lapping film has been around for a long time, much is written about it and it does work well.
You might have better results with a glass tile, (Lowes, 12X3, 5 bucks) lapped flat with a diamond plate or wet and dry, it laps easily. Once you have a lapped flat surface the paper will stick to it very well and you can do anything on it, that you would do with a stone, I haven’t cut or torn a piece in years, since I lapped the substrate flat. You can also lap ceramic tiles flat. Plate glass is not flat, neither are marble or granite tiles.
Personally I find .3um film too sharp, it will exfoliate skin. 1um is plenty if the bevel is properly honed. Try a piece of copy paper under the 1um to polish the edge after finishing, on 1um without paper. You don’t need 100 laps.
Film does leave a very uniform stria pattern and straight edge, and surprisingly lasts a long time. Film works especially well with very hard, chippy razors. And you can’t beat the price, about 50 cents per piece, that will hone 15-20 razors.
It does work, and have its uses, but compared to a quality stone, it is a hassle. Glad it works for you.