#MeshCentral is a really nice, self-hosted replacement for TeamViewer. It has some disadvantages (much worse performance, inconvenient multi-display support, browser based (and therefore issues with capturing key shortcuts)) but also some nice advantages (it's not teamviewer, it's free, you can monitor multiple machines in tile mode, detailed device informations, shell access).
I just onboarded a friend of mine and she is also enjoying working with it.