Textarea::make('public-key')
    ->live()
    ->visible(fn (Get $get) => $get('credential_id') !== null && $get('ssh-key') !== null)
 ->formatStateUsing(function (Get $get) {
  if ($get('credential_id') !== null) {
     $credential = Credential::find($get('credential_id'));
  $client = new ApiClient($credential->id);
   return $client?->getSshKeys()?->first()['public_key'];
                        }
                    })

Textarea::make('public-key')
    ->live()
    ->visible(fn (Get $get) => $get('credential_id') !== null && $get('ssh-key') !== null)
 ->formatStateUsing(function (Get $get) {
  if ($get('credential_id') !== null) {
     $credential = Credential::find($get('credential_id'));
  $client = new ApiClient($credential->id);
   return $client?->getSshKeys()?->first()['public_key'];
                        }
                    })