Is it possible to filter out processes that have not passed a certain milestone?

Alexander, if this is a one-time operation, then you can do it using the process filter
Filter by Business Process and Stages
to do this, you need to select all processes in the "processes" list and use the bulk changes panel to change the value of some additional process field, for example, to "there was no sale", then select the desired stage in the stages filter and tick the "Consider completed stages" checkbox, select the list filtered by the passed stage of the processes and mass changes, change the value of the additional field to "there was a sale"
and as a result, it will be possible to filter by the value of the additional field separately the processes where there was and was not a sale