I've loved Osmo. But have finally replaced it with Thunderbird. I'm using Mikewalsh's Thunderbird portable, viewtopic.php?p=37582#p37582 for the following reasons:
I run several Puppies, and as new ones are published try them, add some to the Boot-Menu and want to keep some information I frequently will access consistent among them. There are two things I want from a PIM: (a) A Contact Manager and a (b) Task list. I don't use the Contact Manager often, but want it when I want it. And occasionally have to edit contacts. Osmo under the NoblePup64's does not even include a Contacts panel. Opening the Task List is the first thing I do every morning. It has to be frequently updated. I've posted to this thread the problems I've had doing that in the older Fossapup64s 
, thankfully not my reinstalled F96. To co-ordinate Tasks and Contacts among several Puppies, moved /root/.osmo into /mnt/home/somewhere/osmo-records, then dragged it back to /root creating a relative(link). Under later Puppies, after starting Osmo, I could rename /root/.osmo to /root/.osmo-O and drag the /mnt/home/somewhere/osmo-records/.osmo into /root, again creating a symbolic link. That didn't work under Exton's NoblePup64. The format has changed. It's now under /root/.config and is no longer a hidden file. That Puppy would not accept as useful any variation in the use of the records at /mnt/home/somewhere/.
After a web-search for PIMs under Linux Thunderbird proved to be the easiest to transition into. Thunderbird can import tasks in ics format. That hurdle was exporting Osmo's tasks in that format. F96's didn't offer an export option. But Bionicpup64 did. Contacts have to be in csv format to be imported. The easiest way to obtain that format may be to export import it to Google-Contacts then export as a cvs. Attempting to avoid Google, I unsuccessfully tried a couple of online converters with the formats Osmo can export. Importing into Google-Contacts should work. Once I realized I would have to use Google, I rememberd it already had my [not updated for some time] Contacts associated with a gmail account.
For those like me who try to avoid giving Google more info than it actually needs, Thunderbird can be configured to keep your information 'locally' that is on your computer, and more particularly when using Mikewalsh's portable, in its own, transferable folder.