Visual studio 19 allows to build an Excel web addin but, apparently, not custom function Yeoman office provides vscode projects for both, separately, but not for the combination of the two.
How is it possible to build a combination of a web addin project combined and a custom function ? (typescript would be prefered)
In a second thought, a workaround could be to build two complements one for the Excel addin and the other for the custom functions. It's not totaly user friendly but should make it, if it's possible to use those two complement at the same time