Which project management system to choose?

Question

Redmine

I have many complex tasks that require careful planning.
In TODOist, I start these projects and split them into subtasks. Convenient in that I see a to-do list for today / tomorrow / a week ahead and overdue. I can also manage these tasks from any device.
When viewing, the Gantt chart is sorely lacking in order to see dependencies and bottlenecks in order to realistically assess the timing of composite tasks.
When adding tasks, it is not clear which days are free and in what state neighboring and dependent tasks will be on the selected date.
In my opinion, the calendar service from Google is very convenient, where you can visually see the selected time period, the overlay of several calendars in order to be aware of the workload. TODOist can export tasks to third-party calendars (only in the premium version, which is given for trial for 30 days). But if I have a Google calendar overlay, I have to edit it in TODOist, there is no reverse synchronization.
One colleague advises me to rent a cloud from Amazon, raise Redmine there ...
Tell me, is there such a system with projects so that it has:
1. Cross-platform (to watch / edit from any device)
2. Tasks and subtasks (nestings and dependencies 4 levels minimum)
3. Gantt chart display (editable)
4. Display of workload as in the Google calendar (with colored labels, it would be generally gorgeous)
5. Adequate price tag. If it's free, it's great, because all my projects don't benefit a single penny.

Answer 1

Everything except this
is in Redmine. It's free.
There is a calendar in Redmine, but there is no layering. If you have any questions about Redmine, please contact