Welcome Kevin!
First, I have no experience in signage applications. But because the answers don't bubble out, let me give some hints.
Where I see possible issues in LibreCAD is the font support. LibreCAD uses its own format and common TTF fonts have to be converted to LFF to be usable in LibreCAD. Also not all fonts are possible to convert.
When the required fonts are available in LibreCAD it should be possible I think.
I assume the text has to be exploded first, what makes each letter a polyline, which then should be recognized by the G-code generator. But the text is not editable as text anymore after exploding it.
If I would have to do this, I'd look if Inkscape is the better tool for this job. It has TTF support and is also capable of DXF export. I think there are even G-code plugins which create CNC programs directly.
I have no practical experience with this too, but I often read, that DIY CNC machines are controlled by Inkscape plugins.
Armin
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