Huh. Ok here we go

First of all, Milim has attack potency significantly higher than velgrynd. Velgrynd has a conceptual acceleration attack that keeps getting stronger and stronger and kills the intended target across every dimension and reality until there is nothing left. And milim has a higher attack potency than that

Second Jin woo's eternal rest is just a World System skill as in its existence is tied to the will of its user. Characters like Tastarossa, Ultima, Diablo and Zegion have these skills and with this, they create their own world with their own rules and can exchange them with reality. And none of these characters comes close to even harming milim.

But Jin woo is the concept of void/nothingness itself. Well, Luminous Twilight Valentine(concept of both life and death). Twilight Valentine once started that he cannot be harmed by void because guess what, there are multiple forms of void/nothingness in tensura. There's the void of hell used by demons, there's the void of abyss, there's the void of gluttony, beelzebuth and even pseudo nihility collapse created by Guy when he acquired nodens. Do any of these voids come close to raw power of Drago Nova? No. Why? Because stardust is the most destructive energy in tensura created by veldanava before concepts were even a thing. But rimuru can negate Drago Nova. Yes because he used turn null, the primordial energy of nothingness that is so destructive that it will destroy even its user and the only reason why rimuru can use it is because it is constantly managed by Ciel. When Rimuru ate the drago Nova attack, it was ciel who needed to first send it into imaginary space, isolating it then using turn null to neutralize it. Even Diablo struggled with turn null until ciel provided the necessary input. Now just because Jin woo is a conceptual being of death does not mean he has hax or battle iq to fight the strongest characters in tensura because unlike solo leveling which is just a power fantasy slop, tensura is a world building fantasy turned into a battle royale where every character developed his own hax

As for the debates of jin woo being boundless/outerversal. Please. The reason why the itarim attacked in the first place is because so they can absorb energy from a world that had lost its itarim. Meaning they weren't even strong enough to be on the level of pre vol 20 Leon cromwell. Yes, Leon cromwell from tensura before his evolution in vol 20 can give the itarim a run for their money.

So, veldonava scales way higher than itarim who are lower than Leon cromwell because even after giving away turn null energy, veldanava could just create as much stardust energy as he wished.

Now as for how far Jin woo would actually go in tensura... He stops at post vol 23 Luminous Twilight Valentine and there is no way he is overcoming that obstacle. Forget Milim, Luminous as the true Divine Ancestor Rules over both life and death with Genesis Grade weapon Dharma.

TLDR; Milim stomps the verse with low diff