Which system should I choose for my Isekai setting?

I've had the idea of running an Isekai campaign for quite a while, but I don't know which system to use. I've only been playing D&D so far, so that was my first thought. I already made up a world and a rough outline for the plot. The players will have to travel to 12 nations to find fragments of the creation goddess's soul and reunite them with her body (very much Zelda). Now, to where I am unsure:

For the final fight, I want to give the player characters powerful, legendary weapons that are basically Divine Objects from Sword Art Online: Alicization. For those of you who aren't familiar with SAO: A Divine Object is a weapon made from animals, plants, or objects that collected "memories" from its surroundings. These weapons are the strongest weapons to exist in the world and are nearly indestructible. Divine Objects can be enhanced by unlocking their full potential. This has two stages: Enhance Armament, which unleashes a special skill like an elemental attack, and Release Recollection, where the weapon releases the memories it has amassed in its previous "life", which would be like an ultimate ability or elemental burst.

I would really like for this to be in my game, but for D&D and a homebrew world, I don't know how many homebrew classes/subclasses/species would be too many (I guess I'd just have to talk to my potential players about what species and classes they want to play). Another system I would like to dm and which would work well with the isekai genre is Fabula Ultima. I'm not too familiar with the system because I don't have the rulebook, but I wouldn't have to worry about species too much because there are no features and traits to species like in D&D. However, I think the Divine Objects wouldn't work out since I didn't find any information about homebrew weapons in Fabula Ultima. Other than that, Fabula Ultima feels like a perfect system for Isekai. Does anyone know a TTRPG that is a perfect match to my idea, while also not overwhelming my players with the amount of choices? Or could there be a way to just re-flavor FU rules to make Divine Objects a thing? I really want my campaign to be a love letter to all my favorite games and anime.

tl;dr: Want to run an isekai campaign where players collect 12 goddess-soul fragments across different nations. For the final boss, I want to give them SAO-style Divine Object weapons with Enhance Armament + Release Recollection abilities. I’m torn between D&D (familiar but tons of homebrew needed) and Fabula Ultima (perfect isekai vibes but not sure how to add custom Divine Object weapons). Looking for a system that fits this idea without overwhelming players, or advice on how to re-flavor Fabula Ultima to make Divine Objects work.