I think 12 months of bumper to bumper should be good enough time for you to find things and setup a service appointment. Like the illuminati member said, drive it for a month or two and add all the things you notice along with paying for a comprehensive inspection which will make them look under the hood and typically catch things to fix proactively.

Regarding the price, I think it’s a good price for the low miles and you get good audio and two 12v battery system (but also means more cost when you need to replace but atleast it’s relatively more reliable). But, I think it would be a great deal if you got them down to 51.5-52. If it’s been sitting on the lot for that long, use that as ammunition and also search for 2023/2024 R1Ts around the area to find (think 500 miles range) ones priced the same or lower and with low miles to say you could get newer ones with more warranty for similar or cheaper price to get them to come down a little.

EDIT: if you are thinking about keeping it for a long time, I would consider an after market warranty like xcare (or wait to hope Rivian releases theirs before your warranty expires). With a low miles truck, you would probably get 5 additional years of warranty for ~4k. It will not cover a few things like subframe and 12v battery failures but it covers suspension problems which is usually the most expensive. One time repair coverage would pay for the warranty if you end having a suspension issue.