IMO it doesn't matter, learning go from Java should not be what excludes you from an offer. Of course if the employer has a choice between two otherwise even candidates then maybe it'd help.
I think the problem is working with both in a production environment is what is going to set you apart.
I'd say learn a language that's really different like a functional or a logic language.
Otoh I've not been interviewing lately so maybe my take is totally off base
I had to containerize an older java app. It sucked, java would take all the memory you gave it regardless, so it was hard to determine memory requirements/limits. It had pretty slow start although this wasn't an issue for us, logging formatting was a pain. All this was overcome (not by upgrading), it was just a pain.
I suspect this isn't true of modern java though - I'd suspect with the hype kubernetes went through a few years ago that it's just fine now a days.