I create a lot of digital-only PDF files, and with the introduction of the Footnotes feature for printed works, adding hover-text for digital works would be an equivalent feature that would vastly improve my and others capabilities with digital products.
In printed works, Footnotes are the only way to give explanations on certain topics, but with digital-only works you are not constrained by the same limitations. Limiting digital works to printed formatting makes the entire experience feel clunky and outdated. The ability for the user to click, tap, or hover over words, images, or other assets and receive an immediate explanation can be crucial. Between blue light, eye strain, and humans' limited attention span, digital publishers only have so much time and space to be both attention-grabbing and informative. Additionally, not needing to account for extra space that footnotes require widely expands the potential design and formatting options.
I switched over to the Affinity series years ago, and hover text has been something I've been hoping could be implemented since day 1. Expanding the digital-exclusive features of publishers would officially make my other current programs obsolete.
I hope this can be taken into consideration. Thank you for taking the time to read this far!