A alternative/subset of https://github.com/neovim/neovim/pull/18506 that should be forward compatible with a potential project system.
Configuration of LSP clients (without lspconfig) now looks like this:
vim.lsp.start({
name = 'my-server-name',
cmd = {'name-of-language-server-executable'},
root_dir = vim.fs.dirname(vim.fs.find({'setup.py', 'pyproject.toml'}, { upward = true })[1]),
})