Is it possible to wrap plugins with nui.nvim?

[ghost]

Intent: Make floating windows and etc. standardized

Is it possible to wrap mason.nvim, lazy.nvim and etc with nui.nvim? If so, where should I start?

[MunifTanjim]

It depends.

If those plugins expose an API to replace the UI, it will be possible... e.g. telescope.nvim supports this with the create_layout API.

If those plugins use the standard vim.ui.* methods, you can override those methods to use nui.nvim. Check the wiki to see how that's done.

Otherwise, it will not be possible. You'll need to ask those plugins' maintainers to add support for replacing UI elements.