Jerky, fruit roll ups, veggies, etc. I like to dehydrate leftover veggies overnight (onions, jalapenos, garlic, etc.) & then grind them up in my blender to make super-fresh spice mixes! I do fruit rollups & other stuff in this flexible pan, which is also super-useful for doing stuff like roll cakes in the APO:
Because it's floppy, I use it on those same grid racks:
They fit in the slots of the APO, they can act as a grid for dehydrating stuff like SV Jerky (soooo good!), and they have little legs, so when you take the pan out, you can stick it right on the countertop to act as a cool rack & support structure for stuff like floppy silicone pans, that way you don't have to use a flat pan on top of a rack to hold it in place & to pull it out. I plan on ordering a bunch more of those grid racks!
If you stretch out the side rails, it will fit, so it requires a little bit of manual labor. I think someone pulled it against some nails or something previously. However, these grid racks fit perfectly:
Also, this smaller breathable, perforated silicone mat fits on top, which is great for stuff like chicken wings as they won't stick on the metal, but you'll still get airflow underneath - much easier to clean!
I also recommend getting a pair of 16x12 pans with fit-in racks, which can act as drip trays, cooking trays, etc. (these racks only fit in the included pans, which are also great for cooling stuff like cookies!):
So that's my current setup. Costs a bit extra, but it's worth it for the convenience & added capabilities!
I can't say about those, but for dehydration I have 7 of these to completely fill up the APO:
https://www.amazon.com/gp/product/B00H94EPJ2/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
I would recommend not getting any assessories, with minor exceptions, and just using whatever you already have. Learn how to use the oven, and you will figure out what you actually need over time.
The main accessories I use regularly are additional cookie racks and sheet pans. There are many brands that fit and are reasonable quality, but these are the ones I have:
https://www.amazon.com/gp/product/B00H94EPJ2/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B07JYY134B/ref=ppx_yo_dt_b_asin_title_o05_s03?ie=UTF8&psc=1
(I would say the racks that come with the latter are not that great, and I tend to use the former cookie racks slotted in above the sheet pans instead. The included silpats are actually useful to block spatter hitting the top of the oven, which is hard to clean.)
IMHO, perforated pans are a complete scam. For steaming veggies or cooking a chicken, just put it on a sheet pan (I usually cover with foil to make cleanup easy) or on a cookie rack above a sheet pan. Again, use what you have, you don't need to buy a ton of accessories for the APO!
Cleaning the oven is a problem, but that's true of any oven that doesn't have an autocleaning function. People tend to use EasyOff, or The Pink Stuff is a non-toxic alternative that I've read seems to work just about as well. I've only ever cleaned my oven once. I just wipe it down with paper towels after each use and live with the grime.