If you're ok working in a text editor, UniteAI works on pdfs, youtube transcripts, code repos, web pages, local documents, etc. The nice thing about the editor is once it's done retrieval, you can hit another keycombo to send retrieved passages to an LLM (local, or chatgpt), and ask questions or favors about it (such as summarization, or formatting changes).
btw pdf support could probably be added to seagoat itself by adding a layer that translates the pdf files to text files and probably some added changed to make sure that the page number is also included in the results