In ISO 45001 the previous requirements for identifying hazards and risks are not drastically changed from the OHSAS 18001 requirements, but these previous requirements only address the hazards and the OH&S risks defined in the ISO 45001 clause 6.1 requirements. Along with what is already in place from OHSAS 18001, you also need to identify other risks as well as OH&S opportunities and other opportunities. While it is possible to document these in the HIRA document you already use, it is not required to do so and in many cases you many not want to especially if the HIRA document is mandated by legal requirements.
So while it might be good to include the OH&S opportunities along with the HIRA document (maybe a new column) as these are related to the hazards, you may want to include the other risks and opportunities of the OHSMS along with other strategic planning risks and opportunities of the company. How they are documented is not dictated in the standard.