Model 85 and speedloaders

Sure you can, as long as the grips arent too wide. If they are, you have options like thinner rubber grips.

When I carry my M85 UL I have 2 HKS 36A on my weak side belt and they work fine with the factory grips.I carry the 85 UL OWB in a thumb break holster.

Depends on the grips. None of the rubber factory grips work really well with speedloaders.

I've got some older HKS 36 speed loaders for my Older M85, they work In 85UL as well, your biggest sticking point will be grips.
You may want to check out speed strips as well, they allow you to top off rather than having to empty the gun then reload.....or carry both. I can carry 2 strips In a case like this https://www.amazon.com/Extra-Small-Universal-Horizontal-Holster/dp/B001AY18U6?SubscriptionId=AKIAILSHYYTFIVPWUY6Q&tag=duckduckgo-ffsb-20&linkCode=xm2&camp=2025&creative=165953&creativeASIN=B001AY18U6

https://www.youtube.com/watch?v=x-fM2lVb2xQ