Yeah, SF4 did the right thing normalizing easy inputs. Now I just wish combos would be easier, they should at least have a variety of low damage auto combos. SF6 has a few low mashing light kick with Mai, but there should be more like that.
Quite a few fighting games have a universal combo string that applies to all characters, and quite literally goes light-medium-heavy. These are called "magic buttons" AFAIK - in contrast to normal "buttons" used to play neutral/footsies. Maybe you already knew that, but that'd strongly help you even with mashing your way out.
Funnily enough, the PS1 port of Marvel vs Capcom actually had a dedicated noob mode, decades before SF6 got one and made it tournament-legal. That one's nerfed, with only two super meter bars and performing certain moves being downright impossible (which makes Ryu, especially when he cosplays Akuma, much less useful - you can't even do a Raging Demon without a TAS because every button is on turbo) - but you do get two autocombo buttons to the left and four dedicated special move buttons to the right.
I play on Switch Lite so I'm basically stuck with the default controls. Technically I think you can connect a controller to it but that's impractical.
Ehhhhh, it's way more practical than you think. Sure, fighting games have gone to great extent to make themselves ultracasual, and even all three of Capcom Fighting Collections have gone as far as to incorporate simple specials and supers - but even then, whenever you play a fighting game,
you may wanna be aware of what direction you're pushing in. And it's not something 98% of "how to fightan for biggeners" videos will tell you; and it's also not something modern OEM controllers are made to do well since the buttons and sticks are made from even purer Chinesium, to make room for 3D rumbles and gyros and mic inputs and whatever the fuck. While still selling for $60 a pop. 80$, for the Switch 2 Pro controller.
The noobification is partially why, for current year goyslop like GG Strive or SF6, fightsticks are less of a nice-to-have, and more of a luxury item. Not the case for poverty fighting games that show up from time to time, such as Melty, though. That said, arcade sticks come with a lot of travel and grinding, for a genre that usually only registers 8 cardinal directions and on/off states for attack buttons, so you may wanna look deeper than that.
Usually, the cheapest and most affordable option for more "tactile" input is a keeb. Sure, the amount of comfort you get depends on the keeb, but say you wanna do a Hadouken, which is QCF. You just roll your two fingers over two keys (so down, down-right, right in quick succession), press the punch button, and voila. That also helps with chargers like Guile, since you won't get accidental horizontal/vertical inputs where it needs to be strictly vertical/horizontal respectively. Cons: mastering people with 360 motions or KOF-level inputs (i.e. Geese Howard's deadry rape) will be like learning to type a Satanic spell.
So someone with arthritis thought that maybe it'd be a good idea to turn that into a proper controller - and that's how Hitbox and its' clones were born. Same cons as before, only this time you don't have all the extra keys lying around, so no one during a tournament's gonna ask if you've bound easy move macros to the whole thing. Depending on the manufacturer, it can also be Switch-compatible, wireless and so thin you can pack it inside of a laptop compartment - they do cost, though. Ironically, for something that comes with no stick.
The "impractical" table setup definitely has merit to it, I saw quite a few photos - and even videos - of people playing Street Fighter on a propped-up Steam Deck, with a Snack Box Micro laid in front, so it's kinda like playing on a bartop cabinet.
Your third option could be fightpads. I know at least a couple that even have a clicky D-pad: 8bitdo Neo Geo Bluetooth Controller and Razer Raion, but the first one isn't compatible with the Switch without an entirely separate dongle, and the second is wired-only and only got two revisions because the first one came with a busted D-pad you could click INTO.
I don't exactly recommend maining the analog stick because it feels extra clumsy for this type of game -
unless it comes with an octagonal gate. So Gamecube controllers and Hori Fighting Commander Octa, if you can get either.
I never played MUGEN so I had nothing to compare it to, but I'm familiar with its concept. I still think it came out pretty well, I'd like a sequel with a lot more polish and options.
MUGEN is as much of a "direct sequel", and prequel, as it could - provided you spend more than one hour on your build.
Man, I lowkey wish Capcom All-Stars was a thing.