Even really good PT can't offset the impact of working or continuing to do activities that aggravate our symptoms.
If PT/ART/DC etc - seem to be helping try to continue the sessions if possible.
TOS isn't a quick fix at all , it takes lots of time..


Here are some things she can try at home, to help w/ posture - many times a day-
The yoga corpse pose is a good start for relaxation w/ diaphragmatic breathing (belly breathing)

and
or
lay on foam roll or large towels rolled up tightly - pillow if needed for neck comfort - then just relax with arms at a comfortable position


You asked for surgery advice..
Most recommend it as a last resort , unless there is something specifically wrong, or showing on tests or imaging.

If you go with that surgeon , make sure he is highly skilled and an expert at TOS surgery and has done many successful operations.
Always best to get a few more opinions.
Of course most surgeons suggest surgery...

Did the dr mention the type of surgery ? rib resection (full rib no stump left behind), scalenes cut or removed, those sorts of things.