Can we install custom ROM without losing data?

To keep them you could use Migrate app and run a backup which creates a zip file which can be flashed along with the custom rom you decide to flash, or use the older methods like titanium backup. But I suggest use Migrate, they have been optimized for android 10.

What happens if I install custom ROM?

Installing a custom ROM puts you in control of your own hardware. You can swap out one operating system for another, tweak more settings, and change the experience until you’re as happy with Android as you can get. Then your phone is truly yours to do with as you please.

Will installing ROM wipe phone?

it will not wipe the mobile data unless its different from what your current rom is. i.e if you try to install the rom without format/wipe-ing factory data and user data. it might display that installation failed due to incompatible data(it means the new android rom and apps that comes with it is not supporting them).

What should I backup before installing a custom ROM?

Backups. The first step to do before flashing a custom ROM is to make a backup of all your data present on the device, including the contents on the external SD card. It is also recommended that you create a “nandroid” backup of the stock ROM itself, which you can restore just in case things go wrong.

How long does it take to boot after installing a custom ROM?

Your first boot into LineageOS will take a while — give it time. You just installed a new operating system and don’t want to rush it! If your first boot takes longer than 15 minutes, something is wrong. Do a hard reboot by holding down the power button until the device restarts.

Does installing custom recovery Wipe data?

from my experience you will not lose your data flashing a recovery as it only flash over the /recovery partition. if you would go to install a new rom it is recommended to wipe everything.