How to get the latest value for multiple fields including corresponding timestamp?

I am storing sparse data in a number of fields where some fields may have a new value every second and others maybe every 10 seconds or 1 minute or even longer.

When querying, I would like to get the latest value for each field including the timestamp.

For example:

time                  field1   field2
2020-03-17T09:00:00Z  null      1.0
2020-03-18T10:00:00Z  2.5       null

I have tried these queries:

Does not return the latest value for each field:

SELECT * FROM "db"."ret"."meas" ORDER BY "time" DESC LIMIT 1

Does not return the date but instead just shows the first possible date (1970):

SELECT LAST(*) FROM "db"."ret"."meas" ORDER BY "time" DESC

Is that possible at all in a single query?

I had some partial success with a query like this:

  (SELECT "field1" FROM "db"."ret"."meas" WHERE "vehicleId"='vehicle1' ORDER BY DESC LIMIT 2),
  (SELECT "field2" FROM "db"."ret"."meas" WHERE "vehicleId"='vehicle1' ORDER BY DESC LIMIT 2)

However, this only returns a single value per timestamp, so if both “field1” and “field2” have a value for a timestamp, then only one of the values will be present in the row.

Edit: I just realised that the missing value was an artifact of the Chronograf UI. Looking at the raw response it looks like all the values are there.