can't tell if this is first ever kayak, or just new one so i will assume that is first ever. this might be informative for others as well
i have same thing like most others:
1. anchor trolley, opted for yakattack hd, mounted on left side (i'm right handed). for actual anchor i have a 5lb (or 3lb?) fitness weight on a 2$ rope from dollar store. holds well enough unless really windy and sandy bottom. you can also buy an anchor for something like $35 if you don;t have a weight lying around or just want something better.
2. garmin striker 4 fish finder, my feelfree moken 2 has a removable center console and i am attaching the transducer to the console. but you can:
- mount it inside although you lose water temp feature and makes it more difficult if you use same sonar in winter as well. there are few guides on youtube
- macgyver something and hook it to the boat somewhere far enough to not interfere with the paddles but close enough that you can lower in water / lift up when getting to shore, e.g. are you considering to add some additional track mounts? perfect occasion to play with a 3d printer
3. phone holder: i have a ball mount phone holder screwed into the console, just below fish finder. if you do not have a fancy sonar, you'll likely still want to have navionics & gps handy. most of the phones can take some splashing these days so you just use your own phone if you do not have a spare.
4. my yak already has 2 rod holders just behind the seat, on each side, but i chose to add another on the track mount for trolling. a bit weirder setup: mount is on the front left side and the rod goes towards the right, thus crossing the yak and extending on the other side. the rod will be in front of you so you can see any bites and also i found it easier to remove the rod
5. get a kayak cart. if you're by yourself, even 5m is a long distance if you don't want to drag it on asphalt or rocks. you have choices: from c-tug, to cheap aluminum carts, to scupper carts, to diy. i got an aluminum one for under $100. not perfect but it does the job. if you get one with inflatable wheels has the advantage that if it falls of kayak, it will float. also the disadvantage that you cannot go too far in the water with it to easily put the kayak on it because, that's right, it will float
6. don't cheap out on paddles. if your kayak was purchased from costco, it likely came with paddles but i think they are a bit short for an sot (i was looking at same kayak last spring) and not that good overall. i would consider using them only for as long as you learn how to paddle and can get an idea on what suits you better (size, weight, paddle shape, etc). there is another post about paddles in this forum) so i won't detail in here.
7. get a a good PFD. depending on the seat, you'll probably be better off with a mesh back so you can sit comfortable, or an inflatable one. again, there is another post about PFDs in this forum, lots of good choices; i got Onyx MoveVent from amazon, and yes, it is certified by canada transprot as well.
Some other stuff, maybe not as popular with everyone else:
imo milk crates (custom or bought) are overrated; i have a milk crate which i never use. i realized that i prefer to get only the lures / bait for the species i intend to target so i keep baggage at a minimum. either backpack or small shoulder bag is set around the seat, behind me, so i can reach it easy if i need to take something out, although i usually keep the most used stuff under the chair or in front of me.
if you are looking to keep what you catch, cheap & effective way i found to keep the fish while still fishing is to get a mesh laundry bag and tie it to the side of the yak, like from footpeg. not fancy but minimum size & weight when not in use and you'll keep the fish alive as much as possible.
i am looking to mount some sort of magnetic plate to keep most used lures exposed, in the sun so i have them handy but also to get dry before storing back in the box. this spring i found a lot of rusty lures & hooks. i have yet to find something that will work properly for my rig though, still searching.
if i recall correctly your yak is not particularly lite, so one way to load it on top of car is something like this:
https://www.youtube.com/watch?v=gC6F_JmzseU although depends a lot on what car you use, how tall / strong you are, etc
if you find that you start getting too many scratches for your taste, or even think there is a risk of cuts / holes, the one thing i've read that you can use on kayaks is gator patch. i am looking to apply it myself but the 9x16 piece (most cost effective) is out of stock on amazon for a while now.
i hope this helps.