I get the same feeling of betrayal, paying extra for an “unlimited” version of what was all the services Proton had to offer and now being left out of all the paid features of Meet, and Lumo as well. And this feeling of betrayal gets even stronger considering there isn't even a package deal for Unlimited users (e.g. buy Unlimited and Meet together, save a few percent)

I agree completely. I would like to suggest more access for Unlimited plans, just like you do for so many other of your services (perhaps all of them).
For Mail, VPN, Drive, etc, you offer basic services for free accounts and expanded services for Unlimited accounts. But not Meet. We have to specifically pay for expanded access for Meet, even if we have Proton Unlimited.
Why?
If you don't want to provide the same level of access for Unlimited that you do with a paid Meet account, then there is this OP idea of more than free but less than paid Meet. This is still a glaring inconsistency, but better than nothing.
Honestly, I have supported paying for Proton specifically because I believe in one of its goals of using the proceeds to offer free encrypted and privacy focused services for those who don't or can't pay for it. Here, having paid for Unlimited Proton offers nothing more when it comes to Meet. It's really not Proton Unlimited, now, is it?

To me, it is more:
Proton Unlimited*

*except Meet.

Yes, one hour seems arbitrary as I have personal video meetings which exceed this limit.
As I am paying for Proton Family this seems not fair.
I have already used other software for meetings because I was not sure about whether I would exceed that limit.

I have the same.
- Great that it's free for everyone in the world for 1 hour
- But I pay € 287,88 (for my family) and have the same limit - doesn't feel fair.

I understand a paid subscription for unlimited meet, but a larger-than-free allowance should really be granted to those that already pay.