For a reference point, when I was unemployed and between jobs, I got involved with Neovim for fun, and after some contributions, I eventually tried some full(ish)-time paid work. I wrote the native lua LSP client (:h vim.lsp, and the nvim-lspconfig repo) for Neovim in a few weeks for about $3k USD (circa 2019)? This amount could fund quite a lot of work to be sure.