I understand what you mean. your bi-fold door does not have door jamb because it does not need one. You can not just mount a door on hinges to the wall, you need a jamb, pre hung door or build a jamb.
The issue you need to deal with is the size of the opening. The size of the pre hung door you want to put in the opening is dependent on the size of the opening. Measure your opening ( this is your "rough opening' I.E. RO ) and get a door with an RO the next size smaller, you can go larger but it requires removing framing instead of adding framing. You NEED an RO that is specific to the door you buy, if you are lucky your RO will not need to be modified but is is unlikely.
The thickness of your Sheetrock on the inside of you current opening is likely 1/2 inch on both sides so if you cut it out you gain an inch. If you have to make it smaller you can put in a 2x4 and shim it so that it gives you the RO you need but this means patching in Sheetrock if the amount you ad is wider than the trim you want to use. So measure your opening and determine what the best door size is, i would say one size smaller, and then get back to us. You can do it if you are handy. If you are in Alaska i can help Or fly me there. :)
The bottom line is you need a RO that is the correct size for the required RO of the door you buy, then you need to hang the door correctly and trim it out.