Got to say I sympathize with those that don't. All of mine including legacy stuff support LinuxVST (2.4) but it doesn't look like the KVR marketplace has me listed. Maybe they don't count free/OSS stuff?
There are whole little communities that do, but you have to dig for 'em. I recently joined Unfa's patreon (reviewer and popularizer of OSS and Linux music-making gear) and joined his discord server. Only to discover they had an emote of my face, due to my OSS plugin making and because they liked my catchphrase 'I'm Chris from Airwindows and hey… you can do this!'
And so you can. The stuff is out there, and if you look around it's absurd what you can do. My favorite discoveries lately are Bespoke, and the Surge Synth ecosystem (hugely impressive and helpful to other OSS projects of all types)
But you'll find it's a bit of a media freeze-out as far as people TELLING you any of this is happening. I can attest that if you do compile your stuff for Linux, you'll hear almost nothing about it, including from the folks you are supporting. I've got a Mediafire mirror for my stuff that tracks downloads across all my updates. Signed MacOSX bundle supporting M1 machines, 3023 downloads. LinuxVST, 325 downloads.
You do Linux support because you care about it as a concept, not because you're going to get any benefit from it. It doesn't pay, it costs (in dev time that won't be compensated, any more than if you were developing one of the little libraries upon which all the Internet depends). You have to have other work lined up to support you while you do the added Linux support.