Back before WWI, several (European) suppliers of 7,65mm and 7mm Mauser Blank ammo used celluloid bullets/wads/hollow sleeves filled with Nitro Powder for both Rifle and MG Blanks.
They are quite rare, nowadays. They were to replace wooden “bulleted Blanks” which, even with a Bullet “shredder” were still dangerous at close range…the Celluloid Bulleted Blanks were not. The Celluloid ( dissolved Cellulose and Cellulose Nitrate Mixture) would ignite and give a larger “Flash” but with no residue to inflict any injuries. (and sufficient “Pressure” to permit Operation of MGs.)
The Fragility and Climate damage to the celluloid eventually caused the abandonment of the idea, just before WW I. The Idea is still used by some manufacturers of “Movie Blanks” for larger calibre cartridges (eg, .50BMG, 20mm, etc, and even Artillery Blanks, such as 75mm and 105mm), but they use synthetic analogues for cellulose, which combust just as well.