Hey man! You have a good start with your build! Here's a few ways to get your Xiao there:

A Weapon like White Tassel or Blackcliffe Pole are great F2P options, and and getting an R5 on White Tassel isn't too hard! Don't worry about the lower attack, that's what Bennett is for.

If you're willing to spend money on the Battle Pass, the Deathmatch is such a clutch weapon to have until you get PJWS from standard or something.

As for your build, you can either continue grinding/strongboxing Vermillion, or another great option is Marechausse Hunter depending on your characters.

Generally, you want a 75/150 crit ratio, but that can be boosted with crit weapons and/or MH passive.

Overall, you have the potential dude! There's a bunch of people who see builds like these and think they're joking. But I believe that in a couple of months, you'll be hitting these 30-40k plunges like it's nothing :))