Cole Palmer is the only City player with much Premier League experience, and that's just under 500 minutes.Good old BBC managed to do an article on who out of the Under 21s is likely to breakthrough into the England Senior team without even mentioning the Captain or the actual goal scorer (and by far the best player for England). Even James Trafford only gets mentioned at the end after Harvey Elliot and Curtis Jones, Gibbs-white and Smith-Rowe. Obviously they had very different blinkers on than me.
Of the four you mentioned, three have 3-4000 minutes of PL football. Harvey Elliott is the least experienced, with around 2000, but he started around half of Liverpool's league games last season.
Clearly those four are safer picks, than players who have mostly second/third tier experience.