Can I active or enable SMBv1 in Catalina?

The short answer is "yes". Keep in mind this is not a Apple sanction answer...

The simple solution is to force SMB protocol versions by modifying /etc/nsmb.conf file.

Solution:

1. Open Terminal
2. Enable Root mode: " type sudo -s" and login
3. Modify /etc/nsmb.conf via nano
4. Sample file (the procol_vers_map = 7 forces SMB1, 2, and 3)

[default]

signing_required=no

streams=yes

protocol_vers_map=7

minauth=ntlmv2

Save and exit Terminal...

Good luck!