WAN Failover with 3G

Would it be possibole to setup WAN Failover with 3G but instead of a 3g router
like in this example:

to use a hotspot on moile phone ?
if so is there example how to set it up?

There’s minimal difference between the wiki example and what you want to do, you only need to create a wireless link to the phone and specify the backup route to use that link.

Phone hotspots can be flaky though, it may not come up up automatically / stay up if the phone goes out of range often

thank you for repling
"you only need to create a wireless link to the phone" - to create that link on new wwan interface?
and if so create the backup route to which interface?
do you mind to share small example ?

Could always use the mwan3 package...

To use a hotspot on mobile phone which may not be always in proximity, you will need the travelmate package. I have tried it, not happy: it scans for the hotspot periodically, thus disrupting connectivity on the AP that is on the same radio. I can only recommend it if the 2.4 GHz WiFi chip will be only used as a link to the mobile phone, or if there are two such chips (e.g. because you inserted a USB WiFi dongle - but then why don't you insert a USB LTE dongle instead).