At worst, the laptop had FOUO/CUI (for official use only/controlled unclassified information) data. Not great for that to get leaked; but not that scary from a national security perspective (we're pretty aggressive about classifying stuff).
If anything damaging comes out of this, I would expect it to be of a political nature; where something that Pelosi and friends would prefer to keep secret gets leaked, but doesn't have much influence on national security.
Even prima fascie top military secrets like battle plans (those must be updated and shuffled regularly to prevent a situation exactly like that) have very little immediate usefulness.
It's 21st century, it's beyond anybody's ability to hide things like size, dislocation, and basic capabilities of your force
Intel reports? Again, most real deal intel sources would be either kept real deal secret, or really not being such.
https://www.ausa.org/sites/default/files/SR-1998-CPMW-Tactic...