I immediately searched the page for 'sftp' but did not find it ... I think your targets of amazon/google/aws are all using the same S3 compatible transport, yes ?
Therefore adding sftp would probably be a big heavy lift ...
It can, I'm using it to mount a Nextcloud webdav share on my more than 7 years old phone (Redmi Note 5 Pro, SDM636 SoC, 4 GB RAM, i.e. close to a potato by modern standards) without any problems.
Therefore adding sftp would probably be a big heavy lift ...