The short answer
Export people and deals from Pipedrive as CSV files, build matching pipelines in HighLevel, then import contacts and opportunities. Activities, automations and SmartDocs templates are recreated by hand. HighLevel's Pipedrive migration guide describes this route, and its help center lists no one-click Pipedrive importer.
Export from Pipedrive
HighLevel's guide says to export contacts from Contacts, People in Pipedrive with names, emails, phone numbers and custom fields, and to export all active and closed deals with their stages, values and linked contacts. Activities, notes and files are exported separately. HighLevel imports CSV only, not Excel, so save any Excel export as a single-sheet CSV. Keep the person name, email or phone columns in the deals file, because that is how each deal is matched to the right contact once it reaches HighLevel.
Recreate pipelines and import deals
Create each Pipedrive pipeline in HighLevel under Opportunities, Pipelines with the same stage names, since imported rows must point at pipelines and stages that already exist. Then run a Contacts and Opportunities import so each row creates or matches the contact and attaches the deal to it. Required opportunity columns are the opportunity name and pipeline; stage, value and status are optional. Map Pipedrive's open, won and lost deals to HighLevel's Open, Won and Lost statuses (HighLevel also has Abandoned). Try a few rows first, because a completed import has no one-click undo.
Activities, automations and documents
Scheduled activities, meetings and follow-ups have to be recreated in HighLevel, so export them before you cancel Pipedrive and work through the open ones first. Automations are rebuilt under Automation, Workflows, using triggers such as a new opportunity or a stage change and actions such as sending an email or text. Contract and proposal templates from Pipedrive SmartDocs are recreated in HighLevel's documents and contracts area, where e-signature and view tracking are set up. Move a few test deals through every stage and confirm each workflow fires before you retire Pipedrive.
More answers in HighLevel questions. For costs, see GoHighLevel pricing or run the cost calculator.