Yes, that works quite well in Agenda.
For example, you can write directly on the iPad with the Pencil, and the Scribble feature converts your handwriting to text.
Adding Text to your Notes
Another option is to add sketches and drawings.
Adding Sketches and Drawings
I once used an older version of Notability and forwarded the drawings to Agenda as PDF files. The problem was the file size. Agenda is not designed for large collections of file attachments.
I use Goodnotes for sketches and handwritten notes. I then send a link to the sketch to Agenda via “Share and Export” and save it in a note. This link allows me to quickly return to the document in Goodnotes. This doesn’t put unnecessary strain on Agenda and I can quickly edit the document in Goodnotes.
I assume that Notability can now do this too.
Give it a try.