Hi, I'm not sure if there is an OOTB feature for generating fillable PDF, although you might want to double check the latest SN PDF Generation API.

There was a possibility to upload fillable PDF templates using Managed Documents plugin as far as I remember, you could then map the fields to SN tables/fields, as well as add a signature field. Those templates can be used dynamically, based on conditions and can be integrated with Adobe sign (theres some integration hub spokes which you might want to check out). I think Adobe should also have an API to programatically generate PDF documents from SN, might be worth investigating as well.

Just some rough ideas, hopefully someone more knowledgeable in current HR features will chime in.