I would wait on purchasing any offbrand Wi-Fi devices for a few months until matter compatible devices are available. They should be easier to add to smartthings and be more reliable. So basically if the brand is not listed in the smartthings app and it’s a Wi-Fi device, I think it would be best to wait for Matter if you can.
As far as the Zigbee model, The Amazon echo devices that have a built in zigbee hub use the same Zigbee profile that smartthings uses, so the one that you linked to should add fine as a simple on/off device without needing custom code. but just to be safe, I would only purchase them from a place with a good returns policy. There are a lot of changes going on the platform right now, and I personally am postponing any device purchases until everything stabilizes. But that’s up to you.