Korean due to it being an alphabe

Technically, it’s not; it’s a syllabary like Japanese katakana and hiragana.

Is it actually that hard while Japanese phonology is considered “easier” to pick up.

Japanese is dead easy for an English speaker so long as they remember that vowel length matters, and the R is not a standard General American R.

Korean has a couple of sounds/features (tense consonants) not in use in General American, but nothing insurmountable. I’d call it more difficult but only very slightly so.

Tone

Korean is actually considered to be undergoing tonogenesis, so that’s kinda neat.

Tone isn’t a huge deal; even if you get it wrong, there’s usually only one thing that makes sense in the context of the sentence. Not a worry in Korean at the moment. Japanese has pitch accent which can cause the same issue (If I’m running through the field plucking はな (hana), you’re not going to think it means ’nose’ here if I get the pitch accent wrong).

One can pick up reading Korean more quickly than Japanese (if no Kanji/Hanzi/Hanja experience otherwise), though I found bacchim to be annoying. In exchange, Korean tends to have some grammatical features lacking in Japanese, but I never got far enough to learn what those were (outside of some more forms of address/honorific).