Not sure if the community is interested in deal posts and digital implementations so why not try both?
The Steam Summer Sale is on and it includes a bunch of digital boardgame implementations. Unfortunately the "boardgame" and "tabletop" user tags are a bit polluted so have to wade through the noise. Here are some standouts I see (USD prices), please add yours in the comments.
- Aeon's End - $1.94 ~~$14.99~~
- One Deck Dungeon $0.99 ~~9.99~~
- Scythe - $7.99 ~~$17.99~~
- Sentinels of the Multiverse $0.99 ~~9.99~~
- Spirit Island $12.48 ~~24.99~~ (all time low I believe)
- Tabletop Simulator - $9.99 ~~$19.99~~
- Wingspan $9.99 ~~19.99~~
Note that some publishers do matching sales on mobile so for example One Deck Dungeon is on sale on Android too.
Edit: relevant BGG forum post with some more