The latest roadmap update that has custom item types under research is to provide more transparency on where the team is on it, rather than folks thinking it would be released soon. The team continues to see the need for our users and community, other items in development have taken longer than expected. Although not in development on the roadmap, custom item types remains on the roadmap as it has significant benefits.
Once this item has started development again (the foundational dB work was completed earlier this year), we will keep the community updated once we have an idea of timing. Thank you for your patience and support.