Krita
Drop-in replacementFreeThe same program, installed from the app store or as a single downloaded file you run directly.
Your files: Opens your existing .kra files, brush presets and .psd files unchanged.
Does Krita run on Linux?
Verdict: Yes
Yes. Krita is free and open source and the project publishes an official Linux build, as an AppImage from its own site and as a Flatpak on Flathub. Your .kra files and brushes come straight across.
Krita's download page lists Windows, macOS, Linux and Android, and the Linux options are a 64-bit AppImage from the project itself plus community Flatpak and Snap builds. The Flathub identifier is org.kde.krita. It is released under the GNU GPL version 3, so it costs nothing.
You will not notice a difference in the program. Same brush engines, same layer types, same animation timeline, same shortcuts. Krita is made by the same team for all three systems from the same code, so features do not lag on Linux.
Copy your resources folder over. Brushes, brush tips, patterns, gradients and workspaces live in a folder under your Windows user profile, and dropping them into the matching folder on Linux saves rebuilding your kit by hand.
Drawing tablets are the one thing to check before you commit. Wacom tablets generally work on Linux without extra drivers, while some Huion and XP-Pen models need a community driver and a few have quirks with pressure or express keys. Try your tablet in a live session before you wipe Windows.
Krita on Linux, and alternatives
GIMP
Different way of workingFreeThe better pick if you were using Krita for photo correction rather than painting.
Your files: Opens .psd, JPEG, PNG and TIFF. It does not open .kra files.
Blender
Different way of workingFreeIts Grease Pencil tool covers 2D animation if that was the part of Krita you leaned on.
Your files: Imports image sequences and PNG files rather than .kra projects.
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