Unsupported frameworks
Here is a list of frameworks and scenarios that have been found to be not be usable due to one or more of the restrictions above. It's conceivable that some will be supported in the future as the sandbox evolves.
PDF generators failing due to restriction mentioned above:
Syncfusion
Siberix
Spire.PDF
The following PDF generators are supported:
SQL Reporting framework: requires the site to run in Basic or higher (note that this currently does not work in Functions apps in Consumptions mode)
EVOPDF: See http://www.evopdf.com/azure-html-to-pdf-converter.aspx for vendor solution
Telerik reporting: requires the site to run in Basic or higher. More info here
Rotativa / wkhtmltopdf: requires the site to run in Basic or higher.
NReco PdfGenerator (wkhtmltopdf): requires subscription plan Basic or higher
Known issue for all PDF generators based on wkhtmltopdf or phantomjs: custom fonts are not rendered (system-installed font is used instead) because of sandbox GDI API limitations that present even in VM-based Azure Apps plans (Basic or higher).
Other scenarios that are not supported:
PhantomJS/Selenium: tries to connect to local address, and also uses GDI+.
Are you looking at removing the dependency on System.Drawing so conversion utilities can sit in the functions?