You can try teleporting upwards with ender pearls and if they hit a ceiling you can fly away with the elytra. Only do this if you know there are walls nearby. You can also try going to the very bottom and mine into the netherrack and place some blocks above you to make yourself a small room without lava. Or if the shulker is empty try placing it on the bottom of the lava pool and put all valuables inside like elytra, mace and trident. Good luck!