Have you tried the Scandinavian 1.e4 d5? It is rare but fine, quite logical, and Black often develops after a scedule.
Looking for an easy to master opening for Black

Scandinavian is a good shout. I play the Sicilian but understand if you are not into that. Pirc seems really solid and FM Nelson Lopez on chess vibes has some solid instructional videos on Youtube explaining the set up and ideas. It begins with a basic set up and most of your oponents bellow 1000 wont know what to do against it.

Set up based and rare compared to what opponents may typically face so you’ll be more prepared.

You can play the King's Indian Defense with the black pieces against anything except 1.e4. Many of the main ideas are easy to master and you can usually play the same 5 first moves and be castled to safety no matter what your opponent plays. I hope this helps.

These types of questions always make me scratch my head. The opening poster plays "he vienna or the italian for white", so he knows something about 1. e4 e5, so (to me) it is entirely obvious to play 1. e4 e5 as black. Yet it is not even mentioned as a possibility. Very very weird.

Presumably OP doesn't like e5 as black. I only play e4 as white but I now only play asymetrically as black Sicilian or Dutch as those games are most enjoyable for me and give variety against my play as white.

You play italian and Viena then it s easy e5! and enjoy playing chess or take no 50 but 5000 hours of your life to study sicilians

if you REALLY want an EASY to master opening, play the stonewall! you can use the formation from BOTH sides (except against 1.e4, 1.g4 and the staunton gambit as black) making it a UNIVERSAL (like kings indians, but without mountains of theory) opening.
me? i've grown to despise it because i don't like closed games AT ALL, even if i scored nicely with it.
i can summarize your plans, as taught to me by the 2200 who turned me on to it, when i was playing the colle...
1. NEVER let your opponent trade HIS queen's bishop for yours! if you have to, develop it to e in front of your king instead of d where it has a line on a kingside castle. if you CAN, trade a knight for it and let your pawns lock the other bishop out.
2. get your king's knight out asap to prevent early queen & bishop checks on the kingside and follow it with your queen's knight trying to get one posted past your stonewall
3. prepare to lift your king's rook after castling to back it up with your other behind it planning an all out kingside pawn storm against 0-0 and the f pawn.
4. pawn storm whichever side your opponent castles on
5. to get your hemmed in bishop active, move to d, then back to e to get around your pawns
6. BEWARE of pawn forks on the e file and/or create your own
and whenever your opponent's castled kingside, just use your pawns to close the queen's side if you must.
if you're really bad against knights though, it might not suit you as they're needed to get past closed pawns, so they like to attack early.
VERY simple concepts with a formation that's hard for your opponents to crack with most not really knowing how. the pawn forks, trading off your strong bishop and queenside fianchettos that win endgames once the center is opened are your biggest threats. that you can use the simple formation against 90% or more of openings is nice too.
the opening served me very well, but it's just not suited to kamikaze attackers looking to mate by 20. you should be able to get up to move 30 against even computers with the stonewall. you might not win or lose until move 60, but trouble is very low in the opening.
so ive been playing the vienna or the italian for white, but i cant find something i like with black; sicilian is out of the question, give me 50 hours a day and i'll think about it, and i dont really like the french or the caro-kann. even though i'm at the beginner level where that type of stuff shouldnt matter, i want to actually understand what i play on black openings instead of just playing nonsense and hoping for the best.