Surjectivity conjecture for the minimal isogeny degree on primes

Let $\mathbb{P}$ be the set of prime numbers, and let $\delta\colon\mathbb{P}\to\mathbb{Z}_{>0}$ assign to each prime $p$ the value $\delta(p)$. Prime-value surjectivity conjecture. For every $n\in\mathbb{Z}_{>0}$, there exists a prime $p\in\mathbb{P}$ with $\delta(p)=n$, equivalently,

$$\operatorname{Im}(\delta)=\mathbb{Z}_{>0}.$$

Thus every positive integer should occur as the value of $\delta(p)$ for some prime. The paper verifies this numerically for all $n\leq50$, but the assertion for all positive integers remains open.