There are many solutions, including the ones you mentioned, providing deployment solutions. Some of them also offer Preview Environments, but it's a by-product (some, like fly.io, don't even offer a dedicated Previews feature). Livecycle is focused on Previews, with the purpose of improving the development lifecycle pre-deployment. That's why we built a collaboration layer on top of these preview environments: we think preview environment can help the entire team, not just devs.
BTW, if you use a deployment solution that has preview environments (like Heroku), we also integrate with that.