The scenario is that after creating lead, someone from the organization will contact the lead through WhatsApp. The chatting functionality should appear in the leads record itself and store the conversation for future purpose.
Bsed on my research yes, you can achieve a two-way WhatsApp integration without Service Cloud, but the best method depends on your goal. Salesforce's native Digital Engagement product is an option, as it can be adapted to link conversations to Leads in Sales Cloud instead of Cases in Service Cloud, but it still requires the paid add-on license and is primarily designed for service. For a pure sales process without Service Cloud, the more common and often better solution is to use a third-party app from the AppExchange, as they are purpose-built for sales, can be more cost-effective, and are completely independent of Service Cloud.
please refer to the links below and FAQ's
https://help.salesforce.com/s/articleView?id=000380726&type=1
https://www.salesforceben.com/whatsapp-salesforce-integration/
https://www.salesforceben.com/custom-salesforce-whatsapp-integration-a-complete-tutorial/
