Been thinking of a medieval sci-fi post apocalyptic setting that would be that years after the apocalypse when the...

Been thinking of a medieval sci-fi post apocalyptic setting that would be that years after the apocalypse when the world is a bit more stabilized and new technology was made that makes guns almost worthless against them (Late medieval looking power armor with melee energy weapons attached to them). the idea being the world descended back to the dark ages yet with even better technology. knights and men at arms wear power armor and ride glories Grav Bikes while the normal infantry uses either non powerd armor and guns.

now the big question is how do I make it not too much like 40k ?

Noble, not grim, for one. Setting on earth rather than in the galaxy as a whole is another big change. The technology being constantly developed, with a focus on energy and science rather than religion and mechanics.

Don't have orks or elves or undead. Don't have highly catholic influence. Don't have dystopic fascist empires as the baseline. Don't have fuck huge pauldrons. Easy.

No, the question is why aren't you playing Degenesis Rebirth?

Make it more sleek visually and less one massive organization crumbling under the weight of its own bullshit and more a bunch of assholes warring with each other over petty shit.

Degenesis is more medieval post-apoc and nowhere near as sci-fi as OP seems to want to take it (with heavy power armour that makes guns nearly useless.)
But you still raise a very valid question, because everyone should be playing Degenesis.

Yeah, you're right.

In fact I'd go so far as to state that although the social and cultural conditions are somewhat medieval, the tech is very much 20 minutes into the future for the most part.

But you could create a more hyper medieval scenario. Say a few Scrapper tribes get together and build a steel castle away from major settlements and trade routes. Then a Paler vault is discovered nearby where sleeper champions armed in hypertech emerge to confront the horse riding lance wielding Scrappers.

Google Too Human. Ignore the crappy gameplay and steal the lore. Its literal technomancy meets norse mythology and any class that uses guns is at such a disadvantage as to bring down the whole teams effectiveness in later levels.

speaking of obscure German RPG, Frostzone is pretty close to what OP describe.

What happens if I scan this QR code?