Why no major Royal Navy lend-lease omission stands out

Was there anything important the Royal Navy should have obtained under lend-lease but did not?

No major gap stands out. The Royal Navy acquired essentially everything it considered necessary through lend-lease.

The answer rejects the premise that an obvious missed category must exist. The Royal Navy drew extensively on lend-lease and secured what it wanted, with no neglected ship or aircraft singled out. That is a useful corrective to counterfactual procurement lists that overlook how broad the historical program already was.