I've never used the steel nibbed pens. My grandfather was a draughtsman, and had a complete set, but as I understood it (age 10-ish) they were delicate and needed to be used carefully. I wouldn't buy a complete set on a whim :-)
https://en.wikipedia.org/wiki/Technical_pen
https://www.rotring.com/pens-pencils/technical-pens/isograph...
https://www.staedtler.com/intl/en/products/technical-drawing...
https://draftex.com.au/collection/pens-markers-inks/technica...
https://www.faber-castell.eu/products/TechnicalDrawingPenTG1...
(There were also Indian websites, so I'll bet there's China/Aliexpress too.)
The 0.10, 0.13, 0.18, 0.25, 0.35, 0.50, 0.70, 1.0, 1.4, and 2.0 scale with √2. I couldn't tell if other sets were just rounding or dropping the hundredths place. The rotring and staedtler both offer sets in those increments. I suppose this is just common knowledge to those who need it.
Is there a term or place to search for pens sets that scale with A*/B* paper? Using the ISO or "technical pen" doesn't return obvious matches (from my US based search at least).