Calling `item.body.getAsync()` with either Text and HTML Coercion produces very different results across OWA and desktop Outlook clients, at least when the body contains elements such as links, bullet points, etc... This has been a known issue since at least 2020 (see https://github.com/OfficeDev/office-js/issues/1248).
Currently, it appears that this behavior will not be changed or fixed, possibly due to preserving backwards compatibility. Instead, I'm submitting this idea to add a new Coercion Type that is guaranteed to produce consistent results across platforms. This can be plain text or a Uint8Array or really any formatting/encoding that would be easiest and simplest.
See https://github.com/OfficeDev/office-js/issues/4111#issuecomment-1956938819