Would the summary then be as follows?
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Run HA + NodeRed on a Rasp Pi 4 with a small SSD or otherwise on a old low power PC, NUC or laptop.
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Instead of buying a Zigbee stick to plug in, buy a Sonoff ZB Bridge, flash with Tasmota and place de Sonoff Bridge at the best spot in the house for best coverage.
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buy the cheap Sonoff Zigbee devices. There is perhaps the caveat that the ZB Bridge can support max 32 devices? Or can it be more if you flashed with Tasmota?
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And if you also want to support wifi controller devices, buy as well the normal Sonoff RF bridge and link to HA platform.