There are NPCs who buy meat
For some other materials, you can also use Settement Warehouses.
In most settlments (aside from Skal) you will find a guy who is a 'trade czar' of some sort. When you talk to him he tells you about prices and amounts of things the settlment uses (wood, stone, cloth, food and metal).
In addition to that, you have the option of 'settlment warehouse' which you can either buy from ,or sell to.
If you explore this menue, you'll see various items that it will buy from you - if it's not already stocked up (Warehouses tend to buy/sell up to around 100 units of most things). If there's still space, you can sell your cotton, or some other materials to them. You can also buy materials from them - if you're looking to craft something.
All the settlments have warehouses, all will probably offer differing prices.
in ADDITION to the warehouse, you also have what I'll call the 'resource stocks.'
'resource stocks' is what I mentioned earlier, wood, stone, cloth, food ect. You can sell these to a warehouse in unlimited amounts, though the pricing will be differenet (probably less) than warehouse.
Grante chunks, marble chunks, bricks, are sold into stone
Various hides and cotton woven into cloth are sold to cloth
Hardwood and softwood go into wood
Meats and food rations go into food
Metal ingots go into metal.
To sell to the settlment all you need do is dump the items into a chest that is nere the settlment clerk, talk to the clerk and chose 'sell items'. The items will vanish from the chest and gold will be given to you, plus a reciept.
Because I know all this sounds a bit complex, I'll use an example, and I'll use Stone as it's easy.
For some ungodly reason, your pc has found themselves with 20 granite chunks.
You go to Bendir, and find that the warehouse says it will buy Granite for 250 per chunk! But it's stock is 90/100.
It says it also BUYS stone for 100%.
You put your 20 chunks into the chest, you sell them. You get 2500 gold of stone which goes into the warehouse, and then the rest (which would be 50gp per chunk - as a quick rule of thumb the value of a resource for stock piles is what it says on the description.) - would go right into the stockpiles and net you a further 500gp.
You can't sell any more stone to the warhouse until someone buys some, or a trade minister moves it to the stockpiles (which they can do), but you can sell it to the stockpiles.
If you put in an item and it can't be sold - either because it's not used, or because the warehouse is full - then it just stays in the chest.
I hope that helps a little?
This too shall pass.
(I now have a DM Discord (I hope) It's DM GrumpyCat#7185 but please keep in mind I'm very busy IRL so I can't promise how quick I'll get back to you.)