We got this one from amazon! Very decent price for the quality! Was very impressed! https://www.amazon.co.uk/dp/B07MLVBS5L?ref=ppx_pop_mob_ap_share
I have the same pram as you and got the top foot muff from John Lewis as recommended above. I got them to fit it for me in store it’s great! You need to loosen the straps a lot though as it is quite bulky
We have the John Lewis Footmuff on our Nuna Triv and I like it. It does fold better without it on obviously but its still a good fold with it on ☺️ https://www.johnlewis.com/john-lewis-baby-lambskin-footmuff-black/p5135764?s_ppc=2dx_mixed_fashion_BAU&tmad=c&tmcampid=2&gad_source=1&gclid=CjwKCAiAsIGrBhAAEiwAEzMlCxm11xkZpvoFUEgr5-YY1chX_XXeTEyTVbMioIqlEOHBBgs2eZPdhBoC5R4QAvD_BwE&gclsrc=aw.ds