Anyone have any real world info on how this works? Can i record onto a zero lines map card and directly use it or i have to upload to a PC in order to use it?

You can RECORD sonar logs to a regular memory card and process the RECORDings with the computer software Auto Chart or Auto Chart Pro, then copy the created maps to a Zero Line Card and it will be read like a Lakemaster map card=primary map.
You can use the Zero Line Card for the RECORDings, but it is best to use a blank formatted memory card of 32 GB or less.

Newer units have built-in Auto Chart Live: described below----

Auto Chart Live has 8 hours of memory for contour map creation. When that 8 hours is filled up, you can delete it or transfer the data to a Zero Line Card (zero lines are shore lines, the card has millions of them).
When you delete or transfer the data from the unit's memory you get 8 more hours to do ACL to the unit's memory.
You can also leave the Zero Line Card in the unit, the ACL map will be created directly to the card, and have enough memory for the rest of your life.
Either way, the created maps are read by the unit with no processing needed.
The maps are OVERLAYED on whatever map background you are using (basemap, Lakemaster, or Navionics).
You can convert that data to a normal contour mapping file type using the computer software Auto Chart or Auto Chart Pro. When processed that way, you copy that data to the Zero Line Card and it is read by the unit as Lakemaster and is a primary map, not overlay.

A newer unit with Auto Chart Live is the best way to do it since you can create the contour map, watch the contour map being created, and use that data right away.
AND you don't need any computer software ever. You can use the Zero Line Card in several units, they all have the same Auto Chart Live software.
You can also share your data with others via Chart Select Auto Chart LiveShare. That makes covering a lot of water faster if others are doing the same body of water. You can see where they have collected the data, then you can fill in the blank spots or resurvey a particular location to get better detail.

If you do the RECORD with your unit, you have to keep your Track so you have a record of where you have been and can cover other areas to fill in the blank areas.

Thank you ! So the bottom line will a newer unit have any better details on the map than an older unit. Provided you go over the same area an equal amount of passes?