So is this a possible diy thing?
Definitely but you should really be getting the surface properly cleaned and polished first to make sure it will adhere as intended and look great. Ceramic coatings do not hide scratches like some filler waxes or glazes so it won’t make a super scratched car look any better. You should be removing scratches with polish and buffers first and then apply the ceramic coating to protect the finish.
If the car is new and in great shape as far as scratches etc go, the application process is very similar to applying wax so you definitely could do it at home. You apply it using droplets of the coating on a microfiber applicator and spread it evenly on the surface and then go back over the area within a few minutes with a microfiber cloth to ensure there aren’t any “high spots”. Do the car in small sections while wiping down with your cloth after.
When coatings first came out, you had to be very quick to go back over your applied sections or it would cure in high spots and worst case had to be polished again to remove those hazed areas. Now, the curing time is much longer in the current versions so it’s much more DIY friendly.
Still not a “fix all” as any car will only look as good as the prep work before applying these coatings so most people are better off getting a pro to apply if there vehicle isn’t in pretty good shape already.