Hi,
I want to periodically backup my external HDD (personal files 300GB+) to B2 and use MountainDuck for browsing online storage and use Duplicacy to backup new files from same source. Can I do this somehow?
communicates with B2 by itself, with no additional help. You should not modify any of the folders or files creates on the bucket as that will break things and you risk data loss.
You can use MoutainDuck for anything else except editing the duplicacy folder in the B2 bucket for the reasons above.
Thank you! That clears my doubt.
The reason why I wanted to use Mountain Duck was - it allows you to mount cryptometer encrypted files that exist in cloud locally on a drive. The decryption happens on demand and dynamically. With Duplicacy, I cannot view the files in cloud unless I download a file a locally and decrypt it 
.
Lastly, can you or anyone comment on how reliable is Mountain Duck - especially the cryptomator feature.
Never used mountain duck :-?
I also never used Mountainduck, but I already used Cyberduck and evaluated Cryptomator.
There is no way to “mount” a Duplicacy storage and access it dynamically for now.
But it is something that every now and then is discussed: Mount duplicacy snapshot as a virtual filesystem
Cryptomator is not a “feature”, but a software, that can work integrated with Mountainduck:
About integration:
https://cyberduck.io/cryptomator/
IMHO Cryptomator still has some bugs and is not completely reliable:
You can find better support in their forum: