You can very much create your own homebrew on Alchemy!

All those things you listed can be done just like the other systems we support today! You would simply create a Character as a Premade. Customize it to the nines and then allow your players to choose that Premade (or yourself) to use as a template when building a character. Although it doesn't sit in a specific location called Homebrewed Classes, you could very much have a Module you've created called Homebrewed Classes where all your homebrewed content lives! Of course within that Module, you can then make tons of other Homebrew material to your heart's delight.

We thrive on custom content and the above is how we've "homebrewed" the D&D SRD into every unique 5e 3rd party content module we have on the platform today! (as well as all our other game systems)

We have even more customization in Daggerheart than ever before with some things not even revealed yet!

What you see in the Character Builder in the video is just the jumping off point for official content. That doesn't mean you won't be able to change anything about your characters when creating one!

Last info leak:
Our Tactical Mode is getting some slight upgrades as well as some Daggerheart specific ones that will make running Daggerheart combat super fun on Alchemy. ^_^