In general, I've had good experience at a previous job with the Samsung T5 series (they are also the Wirecutter
recommendation).
WD has some
SSD Drives with its own Wi-Fi you can connect to and access remotely. However you have to use a web interface or app to access the files, which I don't find ideal. Also from the documentation, it seems that when the drive is connected to a computer by cable, the Wi-Fi module is turned off.
Another option is to connect to your iMac remotely from your other devices and access the SSD drive that way. Any external drive can be used for both Time Machine backups and general file storage as long as you have space
Without more details on the use-case you're envisioning, it's hard to make a specific recommendation.