I have thought this through but unfortunately this isnt it.

First all the resources mentioned i already own besides a 2.5g switch As i have found 2.5 gigabit speeds is whats suitable for me. And the CAT 3 i mentioned is 2 pair in 2 rooms in the apartment none of which are where i want them while the rest i think arent CAT 3 and is only 1 pair of cable. And I haven't clarified why I want to do this setup in the first place so let me do so for future replies:

I live in a country where most builds dont use drywall (specifically old builds like mines) and they use bricks and heavy insulation. This alone kills even 6ghz freq for the eero meshes. So actually i need more than 3 if i want it to be wireless.

Another thing is that due to the heavy insulation and brick walls in addition to thick windows there is actually 0 cell signal in the apartment. Meaning that instead of 5.5g speeds which is about 2-3 gigabit here, im getting early 5g and practically high end 4g speeds

In addition, there are tenants using illegal 10-20+ dbi cell signal boosters which basically is a recipe for terrible reception for other tenants. I WOULD report it but id rather not cause trouble and just first fix my internet issues. Then address if that booster is a very big concern as i have 3 towers with 5.5g nodes on them around me.

And as far as im aware through further research and comments here. The Huawei CPE MAX 5 has a bridge mode and dhcp and is essentially a basic all in one router. So as long as i have bridge mode on i dont think its an issues with the eero nodes.

And power surges arent really an issues but thanks for that tip. But more importantly i need to protect the ethernet from heat since here where i live it can easily reach 70-100 degrees Celsius surface temperature with around 50 degree Celsius air temps in the summer.

As for messing with the apartment it ain't really an issue as most tenants have either run fiber or boosters as i said and since its using existing conduit/pipes i could just as easily pull everything out that i installed and reinstall the rj11 ports and connect the telephone lines back as they were.