I don't really understand the question. Blasting text values into files wholesale is what static site generators do. The web server is operating on the textual values on the disk. You shouldn't need "support" for this, you just use the static site generator to output the desired text into the mass of files it produces. You seem to already know what text you want on the disk, and that seems like 80% of the problem.
I mean, if you really want to add a custom function or two to Jekyll you can, but you hardly need to wait around for "support" for this.
You may be asking for a template that has this built in, but you're just as well off to take an existing template you like and modify the text it is generating than to wait around for someone else to do it.
If it seems like the static site generator doesn't "support" this it's because it's just so "what it does" that there isn't any documentation for how you'd specifically put SSI tags into a site, because that'd just like expecting specific documentation for how you put <h2> tags into a website. It's just what it does already.
I mean, if you really want to add a custom function or two to Jekyll you can, but you hardly need to wait around for "support" for this.
You may be asking for a template that has this built in, but you're just as well off to take an existing template you like and modify the text it is generating than to wait around for someone else to do it.
If it seems like the static site generator doesn't "support" this it's because it's just so "what it does" that there isn't any documentation for how you'd specifically put SSI tags into a site, because that'd just like expecting specific documentation for how you put <h2> tags into a website. It's just what it does already.