This TnT farm is from Ilmango and is actually quite simple. It uses a comparator to detect if a tree has grown and pushes pistons as a double extender with open fence gates to break all the leaves. Once those retract another set of pistons move the wood forward 1 block towards the blast area. There is an automatic dispenser dispensing bone meal all the time (so have a bone meal farm) and all the player has to do is hold right click with saplings in hand.

When the leaves break from the fence gates, saplings fall into an array of hoppers that lead to a dispenser that then dispenses all saplings and sticks to the player (so this is also a stick farm really). The way the machine starts is with an observer looking at a barrel. So when the player opens the barrel, the observer sees the change and starts the whole thing up.

The tnt part is the very basic flying machine tnt duper without the flying part. The tnt is held in place by a series of fence gates that get opened at very specific times by a repeater clock and specific delays going to the fence gates.

The only thing I added was the blast chamber made of obsidian so it doesn't break any of the contraption or anything around it. The collection system is just a water system that leads to hoppers.

Some basic rates, it can collect almost 7-8 stacks of logs in like 5 minutes and this machine can run dark wood, jungle, oak, spruce, and I think acacia (haven't tested this tree yet). The only disclaimer is, with oak trees yo have to have a block to stop growth of the super trees at the top and that is what that sign in the first photo is for. That torch ladder leads to a double piston extender with a block to stop the super trees from growing and breaking the machine.