There are certainly very few, and Linda was certainly an exceptional talent. I can think of at least one other vocalist that I would put in the same league in terms of talent and diverse range, though, and that would be the Australian singer Judith Durham. She was the lead singer of The Seekers during the mid-60's, whose works encompassed pop/folk/rock/jazz/traditional and even gospel. She then went on to have a successful solo career as mainly a jazz performer, while doing occasional reunion concerts with the Seekers (right up to the present day, despite a recent serious medical issue). And her voice had a remarkable purity which Elton John rightfully once observed as being almost unrivalled among popular vocalists.
" I can't think of any another vocalist with her range and talent. "
There probably are some, but I can't think of any either, at least not in the diverse crossover pop/rock/country/jazz domains that she frequented. Definitely unique and versatile.
Best regards,
-- Al