As long as your underlying Debian system stays as close to the stock configuration as possible, it is super easy to maintain long-term. It will upgrade cleanly. You can reinstall in case of hardware failures. There simply isn't a lot of state that you need to worry about.
But once you start customizing your host, you are on your own. This might feel OK for a year or two, but eventually, at some point down the line, it becomes a liability.
Fortunately, there really isn't a lot of a reason why you would ever want to make major changes to the host. Just move all of those into VMs or containers. Containers are particularly nice here, as they can share so much state with the host. In many ways, they are the sweet spot of separating for better maintenance while sharing for easy access to resources on the host.
But VMs are a fine solution too. They are particularly useful for passing through entire PCIe cards. If you only have a single computer and if you plan on using it as your main desktop environment, then you can often pass the GPU and USB keyboard/mouse to a VM and connect your local peripherals as if you were using the host directly. That gains you all the benefits of having a managed environment that is easy to snapshot and backup/restore. This is of course a bit of a hack'ish solution. You wouldn't do that in production. But for a homelab with limited resources, it's great to have options.
