Xiaomi, the Chinese comapny famous for its budget smartphones and a bevy of value-for-money gadgets, said in a filing on Thursday that it has backed more than 300 companies as of March, totaling 32.3 billion yuan ($4.54 billion) in book value and 225.9 million yuan ($32 million) in net gains on disposal of investments in just the first quarter. The electronics giant has surely lived up to its ambition to construct an ecosystem of the internet of things, or IoT. Most of its investments aim to generate strategic synergies, whether…