In our case, they started building on top of our project and then reached out, so not sure I can share any lessons on this. With that said:

- I think administrations in the EU are (slowly but steadily) adopting "Public Money, Public Code" policies and looking more seriously at open source

- Note that policy / strategy on this depends a lot per country / local administration / project etc. I think most governments don't actively develop in house - France is quite the exception in this

- There are a number of conferences that might be relevant (FOSDEM for example just finished)

- We also benefitted from EU grants (e.g.: NLNet) to bootstrap our work and the early research phases