I have had success with Hartz Delectables, Churu, and baby food (make sure it’s ONLY meat, water and cornstarch - no onions!) for powders. And depending on the volume, you can also fill empty gelcaps and dose like pills with a pill gun/popper and/or coated in butter.
Miralax is tough because of texture and volume given… so you really need to either mask it in a large volume of food/liquid (less “gooey”) or something really tasty. I would usually start out with minimum dose and titrate up to effective dose. Also, is cat constipated due to an underlying condition (CKD, for example)? Or a medication (buprenorphine, for example)? My CKS/Panc/SCL kitty was only ever on it intermittently, as needed… then we would taper off.
For small pills, I have success with hollowed out temptations. Bigger pills - pill popper with or without aid of gelcaps. I do find the gelcaps mask taste and you can put multiple pills in one.
I also use a silicone-tipped pill popper for pills… just be careful to ensure that the silicone tip is on securely so they don’t accidentally swallow it (ask me how I know…)
You might also look up the “parfait” method for medicating.
If you choose to syringe liquid medications, aim for cheek pouch or across tongue… cats are very prone to aspirating.