You are using a very old GRASS GIS version (6.4.4 from 2014!) which does not offer v.import as it was developed later.
Please change to GRASS GIS 7.x which is also available for CentoOS7. For this, see https://grass.osgeo.org/download/software/linux/
If you raster's projection unit is meter, then the output unit of the proximity raster will be meters if you specify georeferenced units. In case your raster's projection unit is not meter (e.g. is degree because it is on WGS84), you'll want to reproject your raster to another coordinate system (such as UTM, for example).
QGIS is out, it doesn't support raster attribute tables at all.
I don't know about GRASS.
GDAL would require you to (manually or in python code) handcraft VRTs with lookup tables from the attribute table fields for each "band", then composite the VRTs.
In ArcGIS, you can only use Lookup and Composite Bands. However, look at the versions of those functions ...
A few comments might help:
The -c flag is used to create a new Location using a georefenced file or EPSG code. You should not put the path to your GRASS Location as the value for -c.
FAQ #0: Always set the GRASS computational region before you do any raster processing. So before r.null do:
g.region -ap raster=dummy_img
Instead of starting up GRASS 6 times, ...
By looking at the error message the failure occurs when GRASS (or GDAL/OGR) is trying to create a SQLite table. The SQL create table statement is included in the message, and the error is pointed to happen somewhere near to "from".
The case can be simplified into
CREATE TABLE foo (from);
The command will fail and throw the error message near "from": ...
Here is one solution using ArcGIS:
1) Resample your 30-meter DEM using the Resample Tool. In the Output Cell Size you can write the path to your 8-meter resolution DEM. For the Resampling Technique choose either Bilinear or Cubic, as they are appropiate for continuous data. Also, before running the tool, click on the Environments... button and click on ...
After your comment, I double checked, and this is what I worked out. I start with a multipolygon multi with three areas and two attrib columns cat (value 1) and label (value "one").
# The initial multi_polygon
GRASS 7.6.0 (WGS84):/tmp > v.info -t multi