doogiePIM (PIM=Personal Information Manager) is designed around you so you start where you need to start. eg: If you're a coder and you need somewhere to store snippets of research and code whilst researching the web, then you would start with the Documents section whilst using the browser tabs.
If you're more into needing a way to organize the Events of the day, then you start at the Calendar.
doogiePIM isn't a tool to use for the sake of being there but a tool to use to assist with what you're a doing. Think of it as a Swiss Army Knife.
If you're already happy with your current set-up to manage your Gmail/Calendar then stick with that.
Alas, not soon. I want to take the next few months to add Android import and personal LAN use first. Then I'll think about porting. I am looking at Wine now though.
Might be worth a look at http://strlen.com/treesheets, which is a smaller, OSS, cross-platform swiss army knife based on wxWidgets.
On Android, NoteLynX Pro has some neat ideas, including an outliner item having multiple parents, http://astrodean.blogspot.com/?m=1 Mindscope on iOS also allows an item to be soft-linked into multiple trees/parents for display, with a navigation path back to the original context.
ConnectedText on Windows, DevonThink and Scrivener on macOS have partial overlap.
For mobile: could doogiePIM import OPML files with dedupe? Many existing mobile apps can export as OPML. Could serve as a one-way sync/import.
For archival resilience: will the database format be documented, or could SQLite or XML export be supported? It's tempting to consolidate data into one app for UX/power, but we all know the long term risks.
For mail import, might be worth confirming that MBX import works from https://www.mailstore.com/en/products/mailstore-home/, a free (for individuals) German app that can archive email from many cloud services. Presumably doogiePIM stores email in a standard format.
The cross-linking of data was the primary reason for creating doogiePIM. I've recently added the ability to hyperlink words and images to specific words and other images within the Documents and Noteboard. This is detailed on my dev blog entry here: https://bitespire.com/community/239-one-link-to-rule-them-al...
Major versions are roughly 18 months to two years apart with at least a 50% discount for the upgrade. I was thinking about a subscription basis but thinking from the point of view of a user, I wouldn't like that myself. I think this is a fair compromise - users get a good deal and I get a little something to replace my flux-capacitor every couple of years.
Trust is a huge thing and understandable. This is one reason why I don't trust Cloud storage with very important data. I would rather have my data on my local drive where only I can see it.
I like the idea of some open-source modules. I'll think about how I can do that without compromising security of existing data.
doogiePIM isn't a tool to use for the sake of being there but a tool to use to assist with what you're a doing. Think of it as a Swiss Army Knife.
If you're already happy with your current set-up to manage your Gmail/Calendar then stick with that.
Don't try to fix something that isn't broken.