Some users here use a dock, to which you could connect your external display and backup disc (and, as @ThatNerd said, the Samsung T7’s are a fine choice). Then you can use Time Machine to backup to the T7, and BackBlaze to backup offsite.
As @ThatNerd implied, the experiences of users here using TM has been somewhat varied, and more so when backing up to a NAS. Some people, myself included, have no problems with TM (full disclosure: I’m backing up to a Time Capsule, which is pretty old), others have given up on TM altogether. Arq is a very capable and versatile replacement.