Conversions in GA4 without amount

Maybe last part of this answer could help you: https://support.google.com/analytics/answer/11053133?hl=en#

A new way to represent conversion values
In a Universal Analytics property, you can assign a value to the goals you define. Goal value is the basis for calculating metrics like Page Value and Per-Session Goal Value.

A new way to represent conversion value in Google Analytics 4 is to add a value as a custom event parameter (for example, event_value) to an event, create a custom metric (for example, Event Value) for the event parameter, and then include the custom metric in your reports and explorations.

GA4 events occur when users interact with your website or application. You can mark any events that help your business succeed as conversions by using the user interface. At the point when any of these hailed occasions is set off, a change is enrolled in your GA4 property.