Prometheus + node/container exporters. + Grafana for dashboards I haven’t touched zabbix in years but last time it didn’t support very well dynamic scalations. Also all of them are focused on monitoring infrastructure, you need to pay if you want APM or UX.
Enterprise level, for APM I like datadog, much better than NR. For UX we use acoustic tealeef.
This, I used an old board and it didn’t work until I replaced the (button) battery . After that, you can troubleshoot the board adding components one by one and listening to the beeps. There’s a code. Left the GPU as last element and use the integrated one always until all is working. If a external GPU doesn’t work, it could be not enough power. If memory fails, beeps again, try to find a working one and go from there…