I actually created an over-engineered LaTex template for my invoices, and it was such a pain in the arse. I can't believe I never thought of using Google Sheets or Excel.
I use Python scripts to generate LaTeX invoices/offers/payslips from yaml files. It works very smoothly.
Of course it is more effort than using the built-in templates from the bookkeeping software, but it looks much nicer and I only do a few per month so it is not many minutes wasted.
The effort spent building up these scripts to their current level is perhaps impossible to motivate with any rational arguments... But I had fun doing it!