InfluxQL queries for Data collected by Prometheus

Hi All,
I am using Prometheus with SNMP exporter to fetch metrics from network devices like router, switch, etc. After creating dashboards in Grafana, I realized that Prometheus does not provide downsampling for long term storage over years such that footprint is fixed and small. So InfluxDB is installed along with Prometheus with the intention of using it for long term storage for Prometheus data employing different RPs & CQs for downsampling data depending on retention period.

I want Grafana to now display data from InfluxDB instead of Prometheus.

I find porting PromQL dashboards to InfluxQL for Prometheus collected data stored into InfluxDB a very challenging task. For example, In all dashboards, I use template variable Job (say with value=ubiquiti) to select from available devices and then use another template variable Instance ( value=ip.address.of.device) to select particular device among the pool of Ubiquiti devices.

But in InfluxQL I can either query Jobs or Instances not both.

show tag values from "ifInOctets" with key="instance" 
show tag values from "ifInOctets" with key="job"

Any pointers are welcome.

I have enabled both remote read and write in Prometheus for InfluxDB. Is it possible to keep existing PromQL dashboards with the ability to read historic and current data simultaneously?

Thanks in advance