Logseq looks like a good option for Linux. I still prefer concepts since you get the infinite canvas and more drawing features, but I could probably barely get by with Logseq whiteboards for some topics.

Edit to clarify: Logseq has an infinite canvas implementation that you can draw on but things like the stroke nudge tool are very handy and unique to concepts. I also prefer tap with two fingers to undo which seems to be absent from Logseq. If I didn’t have Windows and Concepts I think Logseq would be good enough.

Edit edit: I tried to launch it again and my pen wouldn’t write even though I had the writing tool selected. Absolute garbage dogshit, and I want my money back.