What do you mean by "factory" ?
The vast majority of M11s are M11/9s which were made by SWD. (save the old MAC/RPB M11s in 380)
Any "factory" suppressor made by SWD would be 20+ years old and ancient technology via wipes, spiral diffusers, and brass eye-loops.
If you are picking up a transferable M11/9 you might as well get a modern suppressor to go with it. If you are talking about "factory" vs. a homemade Form 1 build suppressor than there are plenty of factory modern options available now-a-days that will fit the M11/9 Series.
There are dedicated subgun suppressors like the Gemtech Viper or Bowers Vers 9 that can fit the factory M11 3/4x10 threads that will be right at home on an SWD M11/9.
There are no shortage of other modular suppressors offerings like the AAC Tirant 9(M), Silencerco Octane 9, or Gemtech GM-9 that can be used with the M11/9 by purchasing either an upper with a 3-Lug barrel (and using the appropriate HK style 3-lug adapter) or buying a barrel that is threaded 1/2x28 and use one of the fixed threaded mounts plus associated LID spacer. These modular suppressor while full auto rated have less internal volume than a dedicated subgun suppressor so will have more backpressure vs. a dedicated subgun suppressor. However, they can also be used on a handgun with the proper LID mount as well as other subguns (MP5, EVO9, Colt M16/9) where specialty suppressors like the Gemtech Viper cannot given its dedicated 3/4x10 mounting arrangement.
I would be hard pressed to even bother to pay the transfer tax for a 1980s vintage subgun suppressor unless you just happen to want a collectible. I actually picked up a MAC10 as part of a transferable machinegun package deal back in March and was offered the 80s era can that came with it and refused to take it as it wasn't worth the $200 transfer tax to me.