> What are dev practises like - do people do Agile / Scrum?
Yes. At least what passes for Agile in enterprises.
> do people develop on Linux
Yes. Huawei even maintains its own distro called Euler OS.
> are they using git
Yes. SourceSafe, ClearCase and SVN were used by different teams in the past but have now mostly converged on git.
> are american libraries/frameworks big - are people using React etc?
Yes. Although given the nature of the business, teams that can use a shiny new application framework are a bit of a niche.
> How about things like FP and niche languages
Would you consider TTCN-3 to be a sufficiently niche language?
> is there much appetite for people experimenting with new tech/languages
Containerization and micro-services took hold quite quickly.
> are Python/Java the defacto choices
C is probably the most widely used language but then again it's down to the nature of the business. Java and Python are used a fair bit and Go usage is growing fast.
> Is companies contributing back to OSS a thing?
Definitely. Huawei is regularly one of the biggest contributors to the Linux kernel each cycle. Hadoop, Postgres, OpenStack, ONOS etc. see a bit of participation. There are also projects like Apache CarbonData and OpenSDS that are primarily driven by Huawei employees.