tl;dr: There is an open source project named Ignis which bridges the Electron APIs Obsidian uses and makes it a web app. For syncing, both official Obsidian Sync and LiveSync has headless cli.
I wrote a blog post about my experience with the Minisforum V3 AMD Tablet, focusing on how Linux/Fedora/KDE works on this device and how Linux performs on the tablet devices.
I'm also thinking about reconfigure the Pi to things like PiKVM for remote controlling :)
Hardware encoding requires a GPU, currently I believe the best option is Intel Quick Sync. (Of course if you are using a CPU without iGPU, such as Intel "F" series, NVENC and AMD VCE is also supported by many applications) So it needs to do PCI passthrough to the VM or using a LXC and passthrough it to the LXC container.
One advantage of using LXC than VM is you can share a single GPU between multiple containers at no cost. Technically 12-Gen Intel CPU supports SR-IOV but I'm afraid that the iGPU performance is split among VMs.