From what I can tell it is a niche use case so I don’t expect that the deltachat team will implement this anytime soon.
Delta Chat looks into 2 folders Inbox and DeltaChat for emails, delta chat does not sort according to email aliases. what you could do is make an filter rule in your mailserver to transfer the mails to different mailboxes depending on what alias is in the “TO” header. Then login to those different mailboxes, but configure the smtp login to your main account and set the account email address to your alias, but then, as gerry pointed out, having dedicated mailboxes is simpler to setup.
If you want to use a classical mail client (like Thunderbird / K-9Mail) and deltachat together, but an alias for deltachat then there is a guide for doing this:
Using Delta Chat with email sub-addresses – Lenz Grimmer's random thoughts
Send from different email address (email aliases) - #3 by pcrockett
But there is no solution to ignore emails addressed to a specific alias, maybe that could be a feature request that is simpler to implement, but then it’s an additional setting that needs to be maintained and users can mess stuf up easily but not reading the advanced warnings the we would put in front of it. But nonetheless maybe that’s a version of your idea that could actually be implemented with not too much effort as advanced setting. But then deltachat holds 6 (2x3accounts) simultaneous connections to your mailserver, which might be more connections than your provider allows.