Another rule of thumb - i know it's not always the best since some products are really nice aesthetically - is to buy only local smart stuff, for example, zigbee/zwave.
Instead of Rasp 4s, just get a dell optiplex micro, hp elitedesk, lenovo m920q etc - much more stable, quite low power, and can also use it as a true node, and comes with quick sync for video related tasks.
Install proxmox onto each, create talos VM(s) on each for kubernetes nodes, and you are off to races.
I believe hasura or postgraphile does this for graphql. It's a very niche feature, and kills some of the optimizations if results are further used for filtering, but yes!
Also building https://pricetracker.wtf