Historical bandwidth monitoring

I saw OpenWrt for the first time a week ago, in a modem/router provided by my ISP. The router software has a nice per-device bandwidth monitor feature in the admin interface that I assume is bwmon.

What would be the best way for me to access historical bandidth usage. I'd like to see when devices are using bandwidth, and how quickly devices' aggregate usage is increasing over time.

I've considered looking for a way to take periodic snapshots of the usage table somehow (is there a bwmon or OpenWrt API?) and put those stats into a MySQL database, but there's probably an available tool that would meet my needs without my having to code anything.

Can anyone suggest a product I might look at?

As this is the ISP's modem, I'm concerned about bjorking up their configuration by installing random utilities... is there a way to image the device (ZBT we826q-6 Powered by GoldenOrb_2022-05-05](https://github.com/openwrt/luci) so I can restore it to it's current config if things go wonky?