My point was that José and Chris being continuously employed working on the language and Phoenix respectively (by the companies I named) are probably considered a form of commercial backing by most people. If you want to split hairs about specific timing or magnitude of investment, that's kind of nitpicking IMO. It's not grassroots at basically any point.
José founded Dashbit after Plataformatec got acquired but up until ~2020 Plat directly funded the creation and iteration of the language, with it originating as an internal research project.
https://elixir-lang.org/development.html
José Valim created Elixir in 2012 as a Research and Development project inside Plataformatec.
Dashbit José Valim has openened a new company to help startups and enterprises adopt and run Elixir in production.
Those companies employ a useful fraction of the language core team, too.