That’s an excellent article on the subject, thanks for the link.
To summarize, while most modern equipment has DC blocking capacitors built in for the “important” parts, it simply depends on the design and which parts have them. There’s plenty of instances of meters and such being disrupted etc while PiP is (wrongfully) being sent to them and there’s always the possibility of noise being introduced to other parts of the board. Even if the risk of damaging equipment is relatively low (I still wouldn’t want to risk it), the mere possibility of disrupting features or adding noise also makes it not worth the risk.
I’m going to look into either buying or building a cable with DC blocking capacitors, or just scrapping the idea.
Fortunately I bought this to also record our older relatives when they talk about family history etc and this should be perfect for that; obviously stereo recordings or directly mic’ing them is preferred but some of our older relatives are shy and prefer not to be filmed and such so a discrete mic when they are telling family stories is ideal.