A lot of good advice above! My 2 cents:
I agree the FWB’s are probably the best spring pistols ever made. My issue with them for a long offhand session is not the cocking effort, but weight, they are big guns. The Diana 10 is amazing to shoot too, but even heavier.
As an aside, to me the issue with cocking the FWB’s is not the effort per se, but that the sideways motion is clumsy and can be tough on your wrist and elbow. My work around is to hold the gun on its side (i.e., palm up) in my right hand, then pull the lever up, using an underhand grip, with the left. This seems much more compatible with how my arm is built, LOL.
Another springer I might consider for indoor shooting is the Beeman P1 (Weihrauch HW 45). IMHO it’s the best springer pistol ever made that is not a match gun, period; top quality, high power, with a great trigger. It has two power settings though, in .177 - the lower one being easy to cock, having minimal recoil, and very quiet, great for indoor use. Be aware that using the high power setting will TOTALLY change the POI at all ranges though - not a trajectory thing, but a recoil thing - and will require re-setting the sights. Another advanced feature is the ability to dry-fire the trigger without cocking the gun, enabling effective practice just about anywhere and any time.
I have to jump on the SSP bandwagon, too. You will love the P17, for a gun you can pick up for pocket change at Wally World it is astonishing! My favorite SSP so far though, is the Beeman P2 (Weihrauch HW 75). It’s built on the same frame as the P1 springer. Same lifetime construction, same great trigger, same dry-fire feature, but now totally recoilless and with a lovely stippled walnut grip. The power is low (no more than the lowly P17) but it is a fantastic quality air pistol. I recently shot one for the first time and was bowled over. It sits a bit high to be considered a true full-blown match gun, I guess, but if you want your airgun to mimic a firearm you might consider that a plus.