There should be a number of options out there but those options may not be inexpensive.
Other than the Safariland 6280 you don't give a lot of information about what exactly it is you are looking for. Material? Concealment or Duty or competition? Inside the waist or Belt Holster? Strongside or cross draw? Right or Left handed? Any retention requirements?
I don't have a HK45 so I can't help with specific models. I do have holsters for other handguns from a number of different manufacturers.
I am not a big fan of Safariland. They used to have a good rep as a duty rig/holster manufacturer but their customer service the past 10 years or more has not been good and about that same time period they moved Bianchi production to Mexico and the quality has gone down on some of those as a result which is a shame.
Galco has been a go to for some semi models for two or three decades.
DeSantis has become a reasonable alternative for a lot of firearms. They make a few HK45 holsters. It looks like the common 3 slot thumb snap belt holster has been discontinued. They have it on clearance on their website but if you don't like it you can't return it. They have a couple three IWB models.
El Paso Saddlery has turned out some nice stuff for me. I had to call them as they didn't list the gun I was needing a holster for but on the phone they said 'No Problem!' and I ended up with just what I asked for.
There are a lot of others Don Hume, Kramer, Raven, Blade Tech, John Bianchi is back in the game as Frontier Gun Leather but he doesn't list the HK45 among his gun list. There are quite a few more out there. I've left off the ones I know are no longer in business and I didn't check for the HK45 at most of the ones I listed. I also didn't list a few I really didn't like. Ebay and Amazon are lousy with holster offerings. You might find what you want or someone who might be willing to make what you want there as well.
You have to understand that a lot of resellers are not going to stock holsters unless they are popular. It is a huge overhead and a lot of the time they get stuck with product they can't move. You may have to go direct to the manufacturer and see if they have it listed or even contact them and see if they can make it. Sometimes even on popular models it can take quite a while to get something. Some resellers don't have live inventory and it can take months for what you order to show up so it is often a good thing to call them and see if they have it in stock when you order. Even then Bob may be selling it on another line while you are talking to Mary.
Another option if you are looking for Kydex is you could get some Kydex (or another thermal plastic) and some foam and do it yourself. Some of the material sellers may even sell preforms that just have to be cut out and riveted together but the ones I've seen have only been available for a handfull of firearm types.
Maybe some of the guys who have the same gun can chime in with what works for them.