That was my first thought too. But I think that only works if you have a “virgin” device and have the originally matter-number from the device and to scan at the first use (plug in) of the poweroutlet.
In my nous app there is a function to share the device with “third-party-users”(OH). If you use this function, you get a matter-number which is valid for a while (mine gives you 5 minutes) to link to your system by pairing. I only need it for (re-)generating this number. (perhaps you have a “dummy-e-mail-address” for such purposes)
I didn’t find another way, although I tried a lot of possibilities.
My setUp:
.things:
Thing matter:controller:01 "Matter Controller" @ "Arbeitszimmer" [nodeId="0"] //controller
Thing matter:node:01:nousa8m01 "Nous_A8M" (matter:controller:01) [nodeId="generated by OH", pollInterval=1800] {
Channels:
Type wifinetworkdiagnostics-rssi : 0#wifinetworkdiagnostics-rssi
Type onoffcontrol-onoff : 1#onoffcontrol-onoff
Type electricalpowermeasurement-activepower : 1#electricalpowermeasurement-activepower // manually added - do not work
Type electricalpowermeasurement-activecurrent : 1#electricalpowermeasurement-activecurrent // manually added - do not work
Type electricalpowermeasurement-voltage : 1#electricalpowermeasurement-voltage // manually added - do not work
}
.items
Group gnousa8m "nous_A8M 01 - matter" <a1t_1> (gEG_Buero) ["PowerOutlet"]
Number:Power nousa8m_01_RSSI "Signal" <qos> (gnousa8m) ["Status", "RSSI"] { channel="matter:node:01:nousa8m01:0#wifinetworkdiagnostics-rssi", matter="OnOffPlugInUnit" }
Switch nousa8m_01_Switch "Steckdose A8M" <a1t_1> (gnousa8m) ["Switch", "Power"] { channel="matter:node:01:nousa8m01:1#onoffcontrol-onoff", matter="OnOffPlugInUnit" }
Number:Power nousa8m_01_Leistung "Leistung" <a1t_1> (gnousa8m) ["Energy"] { channel="matter:node:01:nousa8m01:1#electricalpowermeasurement-activepower", matter="OnOffPlugInUnit" }
Number:ElectricCurrent nousa8m_01_Strom "Strom" <a1t_1> (gnousa8m) ["Energy"] { channel="matter:node:01:nousa8m01:1#electricalpowermeasurement-activecurrent", matter="OnOffPlugInUnit" }
Number:ElectricPotential nousa8m_01_Spannung "Spannung" <a1t_1> (gnousa8m) ["Energy"] { channel="matter:node:01:nousa8m01:1#electricalpowermeasurement-voltage", matter="OnOffPlugInUnit" }
I was a bit sad 
about what “matter” can do for me (or not 
).
Have a look on this thread. Same problem !