You have #gitlab where you host your code and pull requests. That tool can also host your issues. You can link them together. Your developers can open PRs and comment on issues. Each dev has an account, gets notified when assigned and has a to-do list in their account.

Now you replace issues with #jira, PRs with messages in a #teams channel, discussions on either of them with calls in teams, notifications with emails and todolists with kanban boards.

So you replace functionality you have in your tool with five other tools and then you wonder why your devs are so inefficient, slow, annoyed and getting new devs up to speed takes ages (because they have to connect all the dots)???

I hope your business fails.

Unfortunately, a lot of devs I worked with in my career so far do not even see an issue here.