OKRs are normally set at the team level and above. IMO individual OKRs are an anti-pattern, unless you’re using them for individual development goals (complete this training, etc.)
Determining the business value of your team’s various goals should be your PM’s responsibility, with input and help from your team.
In your example interaction, the only missing piece is a more specific impact estimate. Rather than “We’re losing customers on this feature because it’s slow.”, you’d want your PM to say “If this feature was X% faster, we estimate that it would reduce churn by Y% per quarter, which is worth approximately $Z/quarter to the business.” Your team can then estimate eng cost to make that improvement, and see where the benefit/cost ratio falls relative to the other things you can be working on.
Determining the business value of your team’s various goals should be your PM’s responsibility, with input and help from your team.
In your example interaction, the only missing piece is a more specific impact estimate. Rather than “We’re losing customers on this feature because it’s slow.”, you’d want your PM to say “If this feature was X% faster, we estimate that it would reduce churn by Y% per quarter, which is worth approximately $Z/quarter to the business.” Your team can then estimate eng cost to make that improvement, and see where the benefit/cost ratio falls relative to the other things you can be working on.