There is nothing preventing SolclientJS from working in react-native or phonegap or other frameworks. That said, it’s not something we actively test in QA. I believe there have been some customers give it a try but I am not sure if they were successful or not.
I am in product management at Solace and we would certainly be interested in hearing your results if you decide to give it a go.
Feel free to share here on the community and we can all help out as you go.