> So, given that the frontend build is baked into _any_ application build, if you decide to do template rendering in any language other than JS/TS, you are adding another build to your project. That means you need to configure that build for all environments, configure CI, and support that build going forward. Save yourself the trouble and just render everything server-side in JS.

You had me until the last part which seems to contradict everything you said beforehand as you now have to test everything being rendered server-side. Why render it server-side if it's already in JS and capable of being rendered on the client? Optimize your bundles if you're chasing lighthouse scores.