Okay I’m wondering if I’ve dropped a ball. I’ve just swapped the chain on my small frame orange 5. The original chain had 111 links. It was okay but in the granny ring / small cog (yea I know you shouldn’t cross gear) the chain would rub on the jockey wheels.

So I’ve taken a couple of links out and It all looks good. However if I take the shock out And rest the rear wheel on the seat tube and it does look a little tight. There is still a bit of movement in the derailleur so I’m assuming it will be okay? Or am I heading for certain death?

If the mech still has a little movement left in your big to big combination at the point in the suspension travel that needs most chain (probably but not definitely full compression), then you are fine.

However if I take the shock out And rest the rear wheel on the seat tube and it does look a little tight

As at full travel, your rear wheel doesn’t hit the seat tube, you’re fine
assuming that’s in your biggest/biggest gear combination.

As you would almost never be hitting a big compression in that gear combination, you’re still fine.

My 1×10 (32:11-42) is set with chain length in 32:32 at max compression.
Chance of me running 42 or 36t rear gearing on the way down hill is pretty small.