Those pull-out strings often don’t work as intended and the handle rips off (even said so in youtube-videos describing the process). Isopropyl alcohol helps, but you should use it with caution and as little as possible. I seem to have used a bit to much isopropyl on an Xperia X, and now the backlight is cloudy.
It is doable, but removing the back at first already needs some special tools (A household hair dryer was not doing the trick for me to heat up the adhesive).
If you don’t buy a new back cover, you have to deal with a replacement adhesive seal, which is a bit fiddly to apply.
Was a bit easier on my old Motorola flip-phone, where the battery was simply clipped into the back of the device, and you could carry a spare for quick swap, or get a larger battery with more capacity.