I have published an experimental package that allows rendering a Mithril component into an HTML string, intended primarily for use with blade templates.
This is both a blessing and a curse. It's not a very good solution for the problem it aims to solve, but it does solve it so I'm giving it a try.
The main reason for this is to make extendable emails that other extensions can extend using the same frontend API. That way ItemLists don't need to be re-implemented in PHP and existing components from
common namespaces can be re-used on both the forum and emails.
I published a 1.0 version because I need semver tags, but it's still very much a beta product.
This package will be integrated into Flamarkt 0.1 to render emails (order and product summaries), though it will only be used with an async mail queue.
The README on GitHub explains how it works https://github.com/clarkwinkelmann/flarum-mithril2html