Hey Eric,
Thanks for reaching out.
ICS is the primary method, though as you mention it has its limitations.
The WordPress XML import/export tools, while not automatic, include all event data and may be helpful for your needs. We have a guide about using those for events here → https://theeventscalendar.com/knowledgebase/using-wordpress-export-tools-to-migrate-events-content
Let me know if this helps! If those tools aren’t what you’re looking for then the best thing alternative to that would be to get a CSV-export plugin from WordPress.org (there are many—we don’t recommend a specific one, just search for one with high ratings). You can then export events into CSV, then import them on the other site with The Events Calendar’s built-in CSV importers. You can read about the CSV import methods here: https://theeventscalendar.com/knowledgebase/using-the-events-calendars-csv-importer/
Please let me know if this information helps and if there are any other issues or questions I can try to help with.
— George