The old v1 has no official repository but it can still be downloaded from https://fancybox.net/ (that one has no SVG support!) … there are several spin-offs that can be found on Github such as https://github.com/andreacampi/fancybox/network with 3 forks and https://github.com/nvidoni/fancybox/network with 2 forks. Not sure if any one of those has added SVG support.
FancyBox v1 in this plugin indefinitely? Cannot promise that but I’ll be keeping v1 in this plugin as long as I can ?? but one day WordPress (and all up-to-date themes etc.) will probably move to an incompatible jQuery version so it might get too hard to keep v1…
By the way, I do not think the v3 license means you have to contribute to use it on a commercial web site. I think it means a contribution when you plan to sell a product (software, app or web site) that contains fancybox… but you might want to ask the developer on https://twitter.com/thefancyapps to be sure.