This repository contains some textures that I've upscaled using Upscayl: https://www.upscayl.org/#desktop, optimized to Steam Deck (handheld mode) using Steam Deck, so don't expect 4K, they are upscaled only to 720p (3x the from original textures).
They are to be used on Citra Emulator: citra-emu.org
Optimized using pngquant: https://pngquant.org/
I know that some of them will be probably incomplete. :) enjoy.