Jujutsu is “just” a piece of software that you install, and it is free and open source. Graphite.dev is a service, and it is not free, but as a service it gives you features that Jujutsu cannot like automatically merging stacked PRs.
For something as fundamental as source control in this day and age, I’d go with the former open source option (and have recently been learning Jujutsu)…
Gross.