although i have no idea what this potential stellar engine might look like, i do have a reason to believe we can harness energy from black holes (and subsequently use said energy) using stellar engines. ways of gathering energy from black holes include hawking radiation and accretion disks. i call this potential megastructure a nihility propulsor. thoughts? could this work in theory?

Are you thinking about somehow reaping the energy and then sending it to some craft (e.g. laser to a light sail), or are you thinking you'd bring the black hole along with you?

The first could maybe somehow work, maybe, somehow, but the second would need reaction mass, and has a snowball in heck chance of working.

Either way, there's so little detail in your post "could this work in theory?" cannot really be answered.

1 hour ago, Illumina said:

i do have a reason to believe we can harness energy from black holes

How do you plan to put your megastructure in place?