DCEU Superman is Low Galaxy/High Solar System Level At The Minimum.
Allow me to explain.
1 - Superman has not been scratched or bruised at any point over the course of 4 movies (MOS, BVS, JL, ZSJL), unless kryptonite was involved.
"B-b-but bottombuckethardo, he was literally shriveled after getting hit by a mere nuke!!!"
Yes, but before like 15 minutes before that, Batman gassed him like a German in Auschwitz twice with kryptonite derived gas. Besides, some 15 foot tall gray guy who's pound for pound as strong and fast as him was going bonkers the whole time before that nuke scene, creating shockwaves that levelled half of Gotham/Metropolis and whatnot.
So in essence, we can assume Superman to be invincible to anything that's not kryptonite. Doomsday was even punching him with a bigger shockwave than 405mm shells from an Iowa Class Battleship and the Big Blue Boy Scout was unscratched.
2 - Superman is basically faster than anything that exists.
"B-b-b-but bottombuckethardo, he failed to save everyone in the Capitol from some bomb in a wheelchair! Even Quicksilver can do that and he's a joke!"
Ok, you've probably never seen him fight the Flash at such a speed that Wonder Woman is completely still. And Wonder Woman casually catches bullets. Superman wasn't as fast/strong as he is now in BvS. In Man of Steel, he struggled to hold an oil rig while a movie later in BvS, he was dragging a battleship through glacier sheets. Imagine the discrepancy between BvS and Justice League. He gets stronger and faster as he gets older. When he was a kid, he could barely lift a school bus.
"But Flash is faster!"
Ok. That doesn't matter when he literally gets defeated just by touching Superman's lats. Imagine being so fucking powerful that you beat some guy by flexing your lats into him.
3 - Superman hits with enough force to obliterate a solar system, when holding back.
"b-b-b-but bottombuckethardo, he barely punched Aquaman like 100 feet in Justice League!"
He was playing with his food. If he wasn't holding back, he wouldn't have bitch slapped Batman into a police cruiser and would've performed involuntary brain surgery like he did to Shazam in Injustice.
Superman lasers one of Steppenwolf's horns off easier than Homelander slaughtered that crowd of protestors. Steppenwolf was said to destroy a moon while fighting Doomsday by the director. We don't know if it was because of technology, orbital bombardment or what, but it's logical to assume that Steppy, being the monster that he is, destroyed the moon via sheer strength. Since he has no visible scars when undressing for Darkseid to pound his bussy, we can assume he tanked a moon-ending event without feeling a thing. Using some basic arithmetics, this means Superman's heat vision can effortlessly destroy a solar system in as many seconds as it took for him to laser Steppenwolf's horn off.
And he was basically smiling and doing cool combos in normal speed (instead of throwing like 50000 full powered punches a second like he could when trying), so when really trying, we can reasonably extrapolate his full strength punches to be capable of destroying a galaxy.
4 - Superman is invincible to magic, including Infinity Stones
"bu-bu-bu-but comics say Magic >>>>>>>>>> Superman!!!"
DCEU =/= comics. Remember when Wonder Woman tried to lasso of truth Superman? She got pulled in and choked like a bitch.
"bu-bu-bu-but big purple man with shiny rocks solo DCEU!!! He turned people into ribbons, knocked out Captain Marvel and more with his shiny rocks!!!"
I doubt kryptonian atoms/cells can be manipulated by the Infinity Stones. Drax, Mantis and whoever else he dusted/ribboned were cannon fodder. Basically street tier. Some random middle aged billionaire with his nano metals tanked the purple rock for like half a minute. Superman tanked everything in existence, including the axe of a guy who "conquered a thousand worlds".
5 - Superman tanks Stormbreaker and Thanos' Weird Sword/Helicopter Blade
Stormbreaker was basically fodder when Thanos had his armor on. And Thanos' armor is less durable than him. Glancing shots from Stormbreaker did nothing to his armor. Thanos bled from some big hammer arms that a middle aged human punched him with. That hammer arm wasn't even sharp. Superman is way more durable.
"bu-bu-bu Stormbreaker chopped Thanos' head off and Thanos' weird sword broke vibranium!!!"
Vibranium isn't durable. The Hulk dented it (the hulk is sub-building level, weaker than Aquaman) and Thor's lightning (which is normal lighting), Iron Man's repulsors and some robot's laser beam melted it.
Thanos bled from some hammer made from a gold/titanium alloy. Superman takes Doomsdays' punches with no damage at all. Doomsday is Superman level (galaxy level), but probably like 200x stronger because he's the size of an elephant. Just watch the video of 200 bodybuilders losing a tug-of-war to an elephant for proof that Doomsday hits (at least) 200x harder than Superman, which is equivalent to 200 galaxy destroying level.
Summary: Superman tanks punches that can destroy 200 galaxies without a scratch, invincible to everything except kryptonite, moves faster than any character in the MCU (fast enough to just run through anyone, turning them into red mist) and punches hard enough to destroy a galaxy. This is all while holding back, and he's still growing into his powers. His heat vision and frost breath is equivalent to 1000 planets' energy output (since they obliterated Steppenwolf and his axe, and Steppenwolf conquered 1000 worlds. So Superman heat vision and frost breath > Steppenwolf > 1000 planets).