the ian ending makes me jump to Lilian.
Also Miriam.
There is a name I saw recently Mirane.
Marion?
If you like Viv and Vivie, what about Vivia or Viva? There is a name Vivaca as well. Or even Viviana.
Vita is a fun name.
If you particularly like the n ending what about Seren? Or there's the slightly older Lauren, Bethan etc. Which I think are nice names. There's also the name Liv.
Thinking of Vivien Leigh, she was born about 1913 so you could look at lists from then or in the 40s when she would have been popular and influencing names to see if there is anything similar. It's a lot of things that are coming back like Dorothy, Mabel, Ivy, Violet etc. Evelyn is one that seems similar (but very popular now too). Vivian was most popular about 1920, other names of that time that were really popular were things like Daphne, Constance, Marion, Audrey (does this have a similar vibe?), Stella, Jean (I like Jean), Josephine (nice), and Nancy.