This one is a bit annoying and nearly impossible to speedrun.
So all I can recommend is this, play the campaign same as normal, skipping any dark magic upgrades but getting the genie crystals as you can. Focus on farming healing items out of Main Street Area 1 as needed. Most battles caused me no issues with the exception of the final Shantae Showdown and the Dual Barons, both of those required about a dozen or so healing items of various grades to put up with.
None of the campaign is difficult using the default loadout, remember to summon a tinkerbat with LT as you go to help fight off harder enemies.
For those who are unfamiliar with the proper flight method for Risky when doing Risky's hideout, you'll find you'll go much further if you jump, RT to use the hat, at the height of your hat bounce THEN use your canon jump, and after the height of that bounce, RT again to glide back down. Risky can use her hat twice if she uses the canon shot in-between. That will get you across the lava fields to the final battle.
You can teleport back to the cabin to grind health items any time and teleport straight back to the boss fight, so try once or twice, dashboard if you failed horribly to get your healing items back, and then go grind Main Street Area 1 again until you feel you have enough items to proceed.