I like using Accelarade but on long rides when I want to refill my bottles they don't have an easy way to mix powder in

Last century I did i carried a bag of powder and a scoop to mix it in

Does any company make a similar product but in a tablet or pill form?

No, just as a gel.https://www.accelerade.com/products/

I use small ziplock bags to hold drink mix.

A scoop to mix it in??


I use Hammer Gel bottles to carry my drink powders in ... shake half a bottle into a 1 litre water bottle, make sure the lid and mouthpiece of the water bottle are closed tightly and shake to mix. Easy.

35mm film canisters work well too.

JB

I found that an old Nuun tablet tube holds just enough for one full bottle.

Gatorade G2 packets

Grandpa, what's film?

That would be a good serving size, although carrying multiple canisters could get tricky unless you have a bike bag.

I use a funnel, works good :-D

Those are a little pricey.

I use snack baggies and put two scoops, one bottle full, in each baggies. When I get to a rest stop I just tear a corner off the baggie, use it as a funnel and pour the powder in the bottle.