Here is my advice:
Get a rappelling kit from EWO. Learn to use it. Maybe there's a climbing gym or club near you where you can get acclaimated to ascent and descent under supervision, if so definitely do that.
Get a 4-5 6' chunks of suitable hitch cords which will work with your rope. No 2 should be the same. You will decide there is 1 you don't like, 1 you do, and 2-3 you aren't crazy about but are perfectly acceptable. Practice tying a bunch of different friction hitches until you settle on 2-3 you can tie right, every time. You can buy more hitch cord later; this is basically a consumable item so don't run out and climb on clapped-out hitch cord.
Get 3-4 carabiners from EWO or REI or another reputable vendor. I use classic screw-gates but the auto-locking options are a premium upgrade aligned with your BOCO plan.
Get a dynaglide haul line kit from EWO. you can get throwline from elsewhere or use paracord, but the EWO kit is a worthwhile BOCO item.
Get a secondhand saddle from the classifieds. It doesn't really matter which one it is, as long as it fits, because by the end if the season you'll have decided there are twelve things you wish were different about it. You won't know what those twelve things are until you've spent a season hunting out of it, so just buy whatever item your budget and classifieds inventory intersect on. Buy the saddle you actually want next year, after you figure out which one it is. This will probably be a custom item from one of the members here who sell them.
Pouches, bags, (quality) sticks, and other accessories are highly personal and basically interchangeable unless you have highly specific and particular requirements, or insist on matching camo on everything.
If you 2TC you can bypass the whole stick climbing/1-sticking thing, which is a rabbit hole you can spend ages on. Stick a pin in that until next year and just figure out 2TC. You can DIY some fleece dump pouches or support DanO at EWO for spme very jice items. The perfect saddle backpack is on the shelf between the Holy Grail and Ark of the Covenant, so use whatever pack you have and put your attention on figuring out how to safely tie and use friction hitches, and ascend and descend on them.
Watch the JRB videos on the Garda Hitch Foot Loop, and assemble a footloop as per his advice. The ability to hang a paracord pre-set and SRT up a tree, bypassing your main climbing method, is a fast, convenient, and quiet way to hunt a tree a second time. You could, I guess, use a mechanical foot ascender, but I don't really see the point for what we're doing.
Presumably you have your actual bowhunting gear figured out and are just working on the saddle piece.