Twenty CRM provides companies, people, opportunities, and customizable objects. The hard part of moving to another CRM is keeping those links intact.
Export a small sample with one company, several contacts, two deals, tasks, notes, and custom fields. Import it into the candidate and check duplicates, ownership, pipeline stages, dates, and whether each deal still links to the right person and company. Ask a salesperson to complete a normal follow-up, then export the same records again. Check access permissions before loading real customer data.
Twenty's data-model documentation explains its objects and relations. A count of imported rows is insufficient if relationships or activity history disappear.