I have now tried several of the web based packages

Kits.AI.
Audimee
Controlla Voice.
ACE Studio.
Vocaloid.
Murf.ai.
Synthesizer V.
Revocalize.
Emvoice.

None are free that I find and they all look very similar. I am about to push the button for Kits.ai (or Audimee). It does have a 3 day free period, but you have to signup first. They claim you can cancel at any time.

The cheapest package is $9.99 and gives 30 minutes of use (DL?) per month. There appears to be three main Features, 1) Custom voice cloning where you upload a number of examples of dry a-cappla voice and it creates a voice clone, 2) Use the voice clone to convert your vocals (limited in download time) and 3) a collection of audio tools for post and pre processing. I am only interested in using one of the 40+ royalty free singing voices to convert my vocals.

The free demo I used for this purpose sounded better than I expected, but you can not "download" the demo from the web unless you sign up.

BIAB – 2025, Reaper (current), i7-12700F Processor, 32GB DDR4-3200MHz RAM, 1TB WD Black NVMe SSD, 2TB WDC Blue SSD, 1TB WD Blue, 2 TB SK NVMe, 6 TB External, Motu Audio Express 6x6