Reddit reviews K&H Pet Products Outdoor Kitty House Extra-Wide (unheated) Olive/Black 26.5" x 15.5" x 21.5"
We found 2 Reddit comments about K&H Pet Products Outdoor Kitty House Extra-Wide (unheated) Olive/Black 26.5" x 15.5" x 21.5". Here are the top ones, ranked by their Reddit score.
Excellent for indoor or outdoor catsWater resistant construction allows placement anywhereTwo exits with see through doors prevent cat from being trapped by predatorsTool-free assembly and includes removable door flaps!Available heated or unheated and both models include a one year warranty
If you would like him to be an outdoor cat, you'll want to make sure he has a good cat house. Maybe a heated one for cooler weather like this one
K&H Pet Products Outdoor Heated Kitty House, Olive, 20W https://www.amazon.com/dp/B004ZJOH06/ref=cm_sw_r_cp_apa_i_YEG3Cb41B3XVZ
Or this one
K&H Pet Products Outdoor Kitty House Extra-Wide (unheated) Olive/Black 26.5" x 15.5" x 21.5" https://www.amazon.com/dp/B01ECC8CV0/ref=cm_sw_r_cp_apa_i_5GG3CbWTZWNQ8
There are a ton of different ones, so even if you don't need something heated you can find a good weather proof option. You also want to look for a way to keep food out for them, but not out for the entire neighborhood, so think about that as well. I'd also suggest a cat water fountain, so that they always have access to a fresh water source. Standing water inside can get gross, but even more so outside.
These things are a bit expensive to set up, but it'll mean your pets will be safe and comfortable while also saving your apartment.
I am not shaming you or putting you down for your efforts so please don't take this as such.
A lot of what's on your list is superfluous and unnecessarily costly. You could service a lot more cats with a lot less money if you "aimed" better.
For example, those outdoor shelters. You have this one listed. That's a single shelter for $53. You can build at least two shelters of the same volume for the same money: A cardboard box ($2.50) wrapped in heavy-duty plastic (3 @ 59¢, $1.78), lined with sheet foam insulation ($14.98 per sheet = 8 2'x2' panels @ $1.87 each, 6 panels to insulate box = $11.24), with holes cut on either side, clear plastic ($9.98, cut into six roughly-2' squares, two squares per box = $3.33) over the openings, and a moving blanket ($4) for comfort. Add a can of spray foam insulation ($3.78) to "glue" the insulation together and seal the gaps. With that formula you can build a shelter of the same size for $26.63, and that assumes you don't have ANY of those materials on-hand already.
Feral cats also don't need sardines in water or a grooming cat toy, or for that matter pretty much any of the canned foods. They'd be better off with dry food; it lasts longer (less spoilage) and doesn't attract other animals as much. Forget about anything that requires power, like that "heated water bowl", unless you intend on luring the cats closer to your home in which case your neighbors might have something not-nice to say about that.
Cats are excellent survivors. Give them a place where they can be protected from the elements, harness their own body heat, and have a little nosh and they'll be fine.