https://snapcraft.io/labplot is already available. Latest version: 2.6.0 :-(
2.8.1 is in Neon stable: https://invent.kde.org/neon/extras/labplot/-/blob/Neon/stable/snapcraft.yaml
Neon is building snaps: https://build.neon.kde.org/view/Snaps/
2021-03-18: 2.8.1 is now available as snap (stable) on snapcraft.io. Thanks Jonathan!
2022:
Neon repo: https://invent.kde.org/neon/extras/labplot
Stable versions are kept in the Neon/release branches or the stable KDE git branch of your app. Unstable versions in Neon/unstable or the unstable branch of your app (usually master).
Links:
* KDE@snapcraft: https://snapcraft.io/publisher/kde, https://snapcraft.io/search?q=KDE
Docs:
* https://community.kde.org/Guidelines_and_HOWTOs/Snap
* https://jriddell.org/2019/04/23/kdes-snap-packages/
* Jonathan Riddell's Talk: https://docs.google.com/presentation/d/13KVisXrlsrDXzqpr5G2llD33K7yGBwXE2DxByrbFzXM/edit?usp=sharing