Your question requires a few answers as to your intended use of your new airgun.
Will you be bench shooting or carrying in the field, as in hunting ?
Will you be shooting a lot or just a few shots here and there. Sighting in at different yardages can use up a fair amount of ammo and air but once that’s settled, hunting won’t use a lot of air and ammo.
Filling just to the gun can allow a smaller compressor, but you mentioned SCBA’s, so filling a 74 or 97 cubic foot tank makes an Alkin or Bauer a better choice. However, there are several people on AGN that say they have been re-filling their SCBA’s with a variety of chinese compressors. Some have good luck, some have bad luck. The smaller compressors will have more frequent service intervals in either preventive maintenance or catastrophic failure. Obviously your budget will direct you to a choice. High pressure air compressing is very demanding on equipment so spend as much as you can afford/justify. If you plan on shooting a lot, even consider two or three SCBA’s so you can cascade fill, or a portable compressor that you can take to your range and fill directly to the gun. I have two 74cf SCBA’s to cascade with and keep them filled with an Alkin W31 vertical. I do not tether at the range as I don’t mind filling my guns reservoir periodically.
Scopes are an even bigger question filled area. Some folks have very inexpensive scopes that do everything they want and are very happy with them. Others spend a lot of money on great optics and are also happy with them.
Reticle choice and max power is a big question too. Orangeokie addressed scope options pretty well.
To me, scope selection is harder than the gun selection. I have three Element scopes and two Aztec Emeralds and am very happy with them but I am not real demanding nor do I have a very critical eye. I mostly shoot 50 yards or less and pretty much have my scope always set at 8x because my monocular I hunt with is 8x. My hunting is basically pesting on chipmunks squirrels and an occasional groundhog.
Best of luck with your new rifle.