The letters
font should be a font encoded as OML
, not OT1
; you can use CMBright for those and for the OMS
family; a decent substitute for the large symbols can be Iwona:
\SetSymbolFont{operators} {sans}{OT1}{cmss} {m}{n}
\SetSymbolFont{letters} {sans}{OML}{cmbrm}{m}{it}
\SetSymbolFont{symbols} {sans}{OMS}{cmbrs}{m}{n}
\SetSymbolFont{largesymbols}{sans}{OMX}{iwona}{m}{n}
To avoid ambiguity, for new readers landing, it may be helpful, for reference, to have a visual on the unicode blocks.
Tex Gyre Pagella Math has Basic Latin (call it "text", but mappable)
Greek and Coptic ("text")
... lots of other blocks ...
and the Mathematical Alphanumeric Symbols (MAS) block:
and
(Sidenote: Because of the organic way Unicode has developed, some of the more famous mathematical symbols are located in the earlier Letter-like Symbols block:
)
By comparison, the Fira Sans Math font's MAS is much smaller:
Other Tex Gyre fonts (Bonum, DejaVu, Schola, Termes) have a math version -- see e.g. ...\texmf-dist\fonts\opentype\public\tex-gyre-math\
Best Answer
You could use e.g. Fira Math: