For basic backup services, Cloud Station Backup is reasonable. I wouldn't want to do a full system recovery from it (and I doubt under Catalina it would support it), but for basic 'regular' data backup services that are free once you've invested in Synology, it's not the end of the world.
While I've not used it since EMC sold it off, Retrospect for Mac might an alternative to consider for a home backup solution.
Never heard of it. If I were going for tape backup software on the cheap for Windows, I'd look at Retrospect, which has been around for a long time. It isn't free, but it does the job, and for SOHO stuff, it isn't too expensive. I used to use this for years in small environments.
If I were using a LTO drive at home, I'd probably go the Veeam route, Retrospect, or use LTFS with a Windows driver and drag/drop files to tape.