Gammon joint finshed in an air fryer?

Yes it will, the highest temperature ours will reach is 210 degrees, it will probably take less time than in an oven though so keep an eye on it.

I have no knowledge of the slow cooker so can't help you about that.
However, just treat the air fryer as a very small oven.
It will do everything the oven does but much faster.

So, yes, the air fryer will brown the gammon and do the same job as the oven.

what Jane said it's trial and error really

Try 10 mins first... I find half the oven time or a minute or two less, same temperature or 10° less.

I’ve often cooked gammon in the slow cooker, usually in cider, it works well.

I have cooked gammon in ovens, slow cookers and air-fryers.

I am still an air-fryer novice but would never use an oven and air-fryer to cook the same thing- to me that destroys the point of having an air-fryer at all.

So, yes I have cooked gammon steaks in my air-fryer and they came out nicely browned but not dry.

I think it depends on the size of your gammon.

I'm not a fan of glazes because I can never taste them in the meat- but maybe warm the marmalade and glaze after cooking? Or serve on the side as a sauce?