External Object as 'Field Type' in Custom Button

Question

Background: Trying to have an S-Docs button created on an External Object view in order to generate a pdf.

Part of this is to be able to create the button within the object, in this case having the custom button on the External Object that effectively references itself. Unfortunately, when looking at the pick list for 'Field Type' in the button definition there is no value and the validation on the field fails upon save.

Answer 1

https://help.salesforce.com/s/articleView?id=sf.links_considerations.htm&type=5

On record detail pages for external objects that are associated with high-data-volume external data sources, custom buttons, and links that call JavaScript aren't supported.

Try making a simple aura/lwc/visualforce with your button and embed it on the lightning page (aka flexipage)? Alternatively does list view button option show something? Would be bit awkward but standard beats coding most of the time...