If drug dealers question the police on planting stuff or saying it was someone elses. Can they not request a fingerprint test?

That would be the wrong approach. First big problem is that cops or anyone else can wear gloves. Second, you aren't really trying to prove who owned the drugs. You would be interested in proving that the space in which the drugs were found previously did not contain the drugs before the cops "found" them. That's why bodycams are super important. Most evidence tampering cases boil down to "spot was clearly empty before cop mysteriously produces drugs from the same spot"

First big problem is that cops or anyone else can wear gloves

Obviously we have to ban gloves

i think with fingerprinting, it provides evidence that someone touched something, not that someone did not touch it

If a police officer is planting drugs, what makes you think the department they’re a part of would take the suspect’s complaint seriously and/or not just mess up/deny the fingerprint identification process?

The request would be made to the court during discovery and, if it was granted, the test would be done by an independent lab. The department could lose/destroy the evidence before it could be tested but that would likely prevent the evidence from being used at trail and it's hard to prosecute someone for a drug offence if you can't tell the jury that you found drugs. Ultimately it's not a great plan anyway. If they didn't find any finger prints then the prosecutor will find some "expert" to testify that drug dealers always wipe down their baggies and wear gloves, if they only find the officer's finger prints then he'll testify that he accidentally handled it without gloves while logging it into evidence.

You can request all you want but it doesn't mean the cops will do shit about it.

or saying it was someone elses.

most countries' drug laws don't have a mens rea requirement – if the drugs are in your pocket, in your home, in your car, then they are legally your drugs

Fingerprints are fake science and not really admissible in court these days. You actually do share your fingerprint with other humans, at least on the scales we can measure it, and thus it's unreliable. The only reason it works for phones/etc is that a 1 in 50,000 false positive rate is "good enough".

https://www.bu.edu/sjmag/scimag2005/opinion/fingerprints.htm#:~:text=Critics like Simon Cole%2C a,a troubling pattern of errors.

After 6 months of waiting for the test to come back from the state lab:

results inconclusive

Fingerprints are fake science and not really admissible in court these days. You actually do share your fingerprint with other humans, at least on the scales we can measure it, and thus it's unreliable. The only reason it works for phones/etc is that a 1 in 50,000 false positive rate is "good enough".