So I am for the most part a lurker and a hobbyist. I've always been a bit of a techie, but over time decided I wanted to be more anti-consumption and such.
I started out with by doing my own calendar. I have a desktop that has my nextcloud and use it to sync my gnome calendar with fossify (with davx5). This was rather straight forward and gave me a nice confidence boost. This is mostly done on my local network, tho I am thinking of reading more into tailscale and getting a domain. The next move I did was to bring my todo list over. This was a bit tricky as many apps don't have a setting to support repeat todos and crossing one off might just remove the item entirely and kill the resets that another app set up. At one point I found the app super productivity. This app is basically perfect. Only downsides is that it is a bit more strict (particularly on the mobile app) about an ssl cert. There is an option to have the app sync with a local file. I thought I could be clever and just have nextcloud do the syncing and let the apps think they are working only off the local on their respective device. Alas there was a snag here. For some reason nextcloud will write the files with read only permission on the laptop, so I cannot add or cross off items. Then I remembered using some apps around a decade ago that worked off a todo.txt file. I figured maybe I could find some mobile and desktop apps and recycle the idea of letting nextcloud manage two way sync of a file and letting apps interact with it as if it were local. It seems like I have some winners here with sleek on desktop and ntodo.txt on mobile.
Just my humble story of selfhosting so I don't feel like a poser when listening to podcasts or lurking.
I am running things locally. I cannot get an ssl cert for my local network stuff because i cannot prove i own it to the issuer (i think?). As far as the todo apps, from what I dug up its that caldav does not support recurring stuff on the todo stuff? At least the default nextcloud app does not. You can set a recurring to do with an app that does, but sometimes i would cross it off on mobile and it would no longer show up on my desktop. It seems that they all internally juggle how recurring stuff happens and diffrent clients might trigger another one to see it as done and no need rescheduling.
Sorry, I missed that. It invalidates part of my comment.
You can make a self-signed cert. If your mobile app does not have an option to accept it ("ignore SSL errors") then it won't work, maybe there's an alternative?
CalDAV is a protocol, which remains the same. The server has little to do with how apps handle things. I have no experience with tasks, but under the hood it's just another calendar and does not treat recurring events differently. I'm guessing these limitations/inconsistencies are app specific.