You can use water or spirit/alcohol based stains/dyes on it. Spirit/alcohol stains are easier to use IMO, but tend to penetrate further than water based stains, so are more messy when you've got binding to think about, but you don't. You'll want to thin the stain, so for spirit stains you can use isopropyl alcohol (hard to get ATM) but I've used meths without any issues.
Both types of stain are fine regardless of the finish going on top. The water/alcohol is only the carrying medium for the pigment and will evaporate off before you apply any other finish on top.
Always err on the weak side with stains. You can always add another application of stain, but you can't remove an application that's too intense.
I generally use these suppliers for equipment and finishes these days: