SM-A520F | Android 7
What I've tried: I partitioned the sd card using minitool partition wizard. I partitioned it into 100gb fat32/exfat and 20gb ext4 partition. I was able to install apps onto the ext4 partition and read things from the fat partition. However, there was a couple problems. I could never see the ext4 partition, all I saw was the internal storage (32gb) and the sd card fat partition (100gb) so I didn't know anything about the sd card ext4 partition.
Secondly, on reboot the fat partition would not mount. I would have to take out the sd card out and put it back in to get it to work. Thirdly, even when the fat partition would mount it would not show up in windows mtp. When I plugged the phone into the computer all that I could see was the internal storage, so if I wanted to put anything onto the sd card I would have to take it out and put it into the computer.
I've used this adoptable storage module to enable installing apps on sd card. It "worked" but I face two problems with this: solid explorer only reads the sd card so it says I'm only getting 120gb (not 120gb + 32gb) and secondly it doesn't load magisk modules properly, so vanced youtube or viper4android don't work. Also now I can't get reverse this.
I've been trying for a while now, I would really love some help.