Thanks for your long and good answers.
I think I'm more comfortable with the more flexible router solution then having to come back later saying they have to buy more stuff to fix my bad decisions
Your first suggestion sounds good, everyone Will get at least minimum speed but more is available if there is unused bandwidth. It doesn't have to be absolutely fair (I guess this wont be) since they don't know how much the others use.
Sure, I understand I should leave some headroom to max speed so latency isn't ruined.
PCQ was suggested in the other thread I started before your post. I guess the packets can be marked on subnet and not only on single IPs? People will probably use only one computer anyway so it might not be a huge problem. None of these is a computer expert anyway I guess as they asked me to help them
Yes IPv6 vill be a blessing hehe, no more resource hungry NAT
I guess they will use one of the most IPv6 friendly ISP here in Sweden
Yes I already thought about your poe suggestion and using hAP ac lite (switch/bridge mode). Depends on what they want but I will tell them that double NAT which they will get if they go out buying home wifi routers themselves is not great...