This list might help with what to prioritise buying.
www.getgetgot.com/what-you-need-for-newborn-baby
In addition to newborn, up to 1 month and 0-3 sleepsuits and vest, I've bought the following:
2 x love to dream swaddles (up to 3 months)
2 x mamas and papas sleeping bags (3-6 months)
1 x carrier
1 x play gym
10 x burp cloths (the thick, layered muslin ones)
Various blankets in different thicknesses including a cot cellular blanket
About 5 thin, large muslins and 1 thick muslin
Hats, socks and bibs
1 x bedside crib
1 x grooming kit
It's mainly because I got great deals on Amazon or new with tags stuff on Vinted.
If you're okay with buying on Amazon I'd suggest signing up to their baby register. You get 15% off lots of baby items, which stacks with their general offers. Every time I log in one of the items in my list is 15-20% off then I get the 15% discount on top.