European startup studio eFounders has now been around for 10 years. And because a birthday sounds like a good opportunity to share some metrics, the portfolio companies have reached a valuation of $2 billion together — only 18 months after reaching $1 billion. eFounders says it is focused on building the future of work. In practical terms, it means the company is building B2B SaaS startups with a focus on productivity and workflows. For instance, Front, Aircall and Spendesk all started with eFounders. There have been a few exits, such as…