The launcher supports passing a server address: see this update info post.
Minecraft <username> <password> <server:port>
<username> is the username you wish to log in as
<password> is your password. If this is set, the launcher will automatically start the game without waiting for you to press the button
<server:port> is an ip to a minecraft server. If this is set, the game will automatically connect to that server once the game has started.
I don't know the definition of tree miller...
[EDIT: as the video I linked to disappeared, thank Robotnik for pointing this out]
But there are a variety of semi-automated tree harvesters out there that are capable of a modest amount of AFK.
The idea is for you to have saplings in your hand, plant one, have a bone meal dispsenser adjacent, which bone meals the sapling.
Once the sapling grows into a tree, a large redstone device, which surrounds a 5x5 area pushes the logs out to a large wood collection area.
If you are daring, you can build an enclosure for a wither, and have the wither blow up the wood, most of which will get harvested.
Saplings are collected in hoppers at the bottom, and moved back to you, so you just have to sit and plant saplings.
There are many tutorials on the topics, in particular, google: Minecraft automatic tree farm (or minecraft AFK tree farm). A video from a more famous youtuber than previously posted is here:
Best Answer
Ilmango recently started a new 1.14 Skyblock series and provided an instructional video along with a full set of tools (links in the video description) to create the entirely empty world (including Nether and End) and adding some tweaks that allow to obtain/produce some resources that would otherwise be unavailable.
(The entire process is rather lengthy and convoluted never mind impossible to perform without the tools linked, so I see no point describing what's in the video here)