I know people who’ve put cask wine in the Sodastream, so why not.
I have a Sodastream, I don’t drink a lot of carbonated beverages (except beer) but when it’s hot and I’ve been working in the yard, nothing like a cold, fizzy beverage. I get the bottles of syrup and use about 25% of suggested doser.
I’ve lost much of my taste for sweetness over the years so I no longer use the sodastream syrups. I do have a bottle of non-sugar “simple syrup” that I use if I need a bit of sweetening. I like the carbonated water with lemon juice, lime juice, or cranberry juice (unsweetened). Sometimes I add ginger. Sometimes I make NY egg cream, but it foams so much that it’s kind of a pain (wish I knew how to control it!). When my kids were little, l’d occasionally make pop using frozen grape juice concentrate.
Try pomegranate juice. That’s my go to.
I take my Sodastream bottles to Walmart to exchange, the new bottle after that costs about $15.
I won’t use Sodastream for … reasons, so thanks for providing the name of an alternative brand. I’ll have to look into getting that here.
My initial review: the greatest invention since fire? Perhaps. It’s close.
I’m sure it will be less exciting over time, but I’m quite enjoying it now.
I’m glad it’s working out for you. 
My wife is looking for seasoned advice on reputable sites from which she can order a mod for our sodastream. She’s seen a lot of suggested devices on reddit and other places, but is worried about putting in CC information on some of them.
And she wants something as close to plug and play as possible. Ours is an older model, still using the “blue” canisters,
It never gets old
This adapter allows you to use a paintball cylinder. It’s what I use.
ETA: Here is the 20 ounce tank