The filtering on the open CFPs page can be improved in the following ways:

• negative tags
• multi-select filter by topic
• multi-select filter by tech
• multi-select filter by language
• not online
• convert existing single-select filters (country and region) to multi-select filters
• Add any/all toggle to all the multiple filters.

I am happy to do it (full disclosure - using Claude code with Intent Integrity Kit). Will you be interested in such a PR?