I've owned both bullpups and standard rifles in my firearms shooting days. In, .22, (custom stock) .223 and .308 (one with a short custom stock) calibers.
In those days, I saw "no" difference in my shooting skills / accuracy in shooting long guns vs. abbreviated guns. This is all off hand / free hand shooting only. Never done any crutch (bench, monopod, bipod, bag) shooting. This is shooting 75 to about 125 yards, all in the standing position. I may have tried the sitting position, but not remembering that positively !
All of my current air powered guns are of the Bullpup design (all but two are under 30" long). And again, I have no trouble shooting off, or free hand, except the accessional day when my 71 hands are a little shakier than normal ! And yeah again, all of my air gun shooting is standing with only my arms to support the gun. Sometimes, on those shakier days, I'll lean my back against the back door to my house for a little support.
I enjoyed my short firearms, I enjoy my short air guns. I also enjoyed my longer guns, that I still own one of, but prefer shooting the short, bullpups more.
While the "iron sight" radius is longer using a full length rifle than iron sights on a bullpup...who uses "iron sights" anymore, I don't ! So...with the barrels being similar in length in either full length rifles AND bullpups, scopes bring the sighting picture to a pretty much "even" playing field, bullpup to long gun.
Mike