What outdoor extender to use to connect two Orbi 860?

Extending WiFi coverage to an outbuilding has two major considerations:

1. How important it is that mobile devices roam seamlessly between the main building and the outbuilding.
   1. If this is an important factor, then only a compatible Orbi satellite will provide this capability.  RBS860 satellites are not all that easy to purchase (even used).  Alas, Netgear does not show any other WiFi6 satellites as being compatible with the RBR860 router.
      https://kb.netgear.com/000065169/Which-Orbi-routers-and-satellites-are-compatible 
   2. If seamless roaming is "nice to have, but I can live without it", then any brand of WiFi access point will be fine.
2. Getting a network connection from the main building to the outbuilding.  If the buildings are relatively close to each other (under 75 ft.) then a satellite in the outbuilding may sync directly to an Orbi unit in the main building.  "Problem solved."  If not.....
   1. If the distance is under 300 ft., the "A" solution is to install an Ethernet cable between one of the Orbi units in the main building and the unit in the outbuilding. The actual cable is relatively inexpensive.  Installation can be quite a chore. (Penetrating two building walls, trenching, laying PVC pipe, etc. etc.)
   2. For distances greater than 300 ft. or where cable installation is impractical, the next best solution is a "wireless bridge".  This appears to devices on each end to be a simple Ethernet cable, but is actually a radio link.  These come in all sorts of capabilities (with prices to match) and are available from major manufacturers, such as Ubiquiti and TP-Link, plus a host of minor players. Search Amazon for "wiress bridge". Then read the user comments to see the sort of situations where people found them useful.
      Wireless bridges are often rated in terms of kilometers, so people often find they can mount both ends indoors and just "blast through" the walls of both structures.  If they need to be mounted outdoors, most models use Power over Ethernet (PoE) which makes getting the Ethernet signal and the electrical power through the wall much easier.