Ooh I like this question and I don't see anyone try to answer this rhetorical answer so I'll give it a go.
First up, since England's 26 man squad is lacking a left-back, so I'd have USA's Antonee Robinson in for Conor Coady. 1/26
Then, England's midfield options aren't the best because they're either out of form, or not fully fit. I'd take all of McKennie, Adams, and Musah (the latter was an England youth player) over Phillips, Gallagher, and Henderson. 4/26
Also, while I do rate Callum Wilson, Iran's Mehdi Taremi has been very prolific for Porto, and has scored a few in the Champions League. They're both the same age too, so that won't be an issue. So I'd have Taremi over Wilson on this one. 5/26
In terms of squad depth and versatility, I'd want Ben Davies in my squad. Someone who could play LB, LCB, and LWB. He'll probably be in my squad for Ben White. While very good and very inform, he plays in a position where England have other better options for (RB, RCB). 6/26
Probably would've tried to squeeze in Aaron Ramsey & Gareth Bale but they're way passed it and wouldn't have been picked even if they were English. Weah, Pulisic, and Reyna might have a shout, but England's got one of the best forward options in the tournament.
So those are my answers. At the very least 6 players from the 3 teams could make the England squad, but there is possibility for that number to be bigger.
I don't know what the point of that was, but it was fun to work out anyways.