rmcjacket23
Ravens Ring of Honor
You only need this page, and one player.i know this isnt what you asked but this (https://www.pro-football-reference.com/teams/rav/2019-snap-counts.htm) has the players snap counts as a percentage so it wouldnt take much to work out the totals off that info - also has each game's snap counts (with players) as a percentage of total by a unit so you can work out total game snap counts too
if you scroll back through jeff zrebiec's twitter you can probably find screenshots of the snap count breakdowns after each game too (again as a percentage of total snaps)
filmstudybaltimore (ken mckusick) does his own snap counts too where in his articles he'll mention the total snaps often that a unit had in each game
but otherwise im not sure if there's other options
Marlon played 962 defensive snaps, which was 98.16% of the total. Divide the two, and you get 980 total defensive snaps for the year.
As you said, same site has game-by-game breakdown also.