After several tests, I believe I achieved the expected result. The mapping is located in the devicenumplanmapremdestmap table, as its name suggests it maps Remote Destinations to specific combinations of device (Remote Destination Profile) and DN. The presence of a record in this table for a Remote Destination indicates that the checkbox is checked, while its absence indicates it is unchecked.
Below is the SQL query for anyone who might need it in the future:
SELECT d.name AS remotedestinationprofile,
np.dNOrPattern AS line,
rp.name AS partition,
rd.name AS remotedestination,
rdd.destination,
eu.mailid,
eu.displayname,
eu.userid,
rdd.enablesinglenumberreach AS snr_enabled,
CASE
WHEN EXISTS (
SELECT 1
FROM devicenumplanmapremdestmap drdm
WHERE drdm.fkremotedestination = rd.pkid
) THEN 'Yes'
ELSE 'No'
END AS line_association
FROM
remotedestinationdynamic rdd
INNER JOIN
remotedestination rd ON rdd.fkremotedestination = rd.pkid
INNER JOIN
device d ON rd.fkdevice_remotedestinationtemplate = d.pkid
INNER JOIN
DeviceNumPlanMap dmap ON d.pkid = dmap.fkDevice
INNER JOIN
NumPlan np ON dmap.fkNumPlan = np.pkid
INNER JOIN
Routepartition rp ON np.fkRoutePartition = rp.pkid
INNER JOIN
enduser eu ON d.fkenduser_mobility = eu.pkid
WHERE
eu.userid = '<USERID>'
