There are other note apps that can sync with Nextcloud. I settled on Quillpad because of its checklist functionality, though admittedly it's not perfect.
It can be slow out of the box, but if you set up locking/memcaching (I use APCu+redis), it's way faster.
I get not wanting to mess with it though. I was at that point until I got more free time. Now I have mine running smoothly, but I had to put in maybe 10 hours to iron out all the things, although that includes upgrading the host OS because it had gotten old. If I had a full time job, I'd probably just pay for a fully hosted NC.
Note: If you are short on RAM or want the simpler version for home/lan use, you can just set up APCu and get a decent performance boost. I got better performance with both: APCu for file locking along with redis for memcaching. But setting up both will be a bit more complicated to setup and maintain.
Six months ago, I was exactly where you are, but updating host OS, then updating Nextcloud to 27, and setting up memcaching worked great for me. Get everything updated before doing the setup, though, or you'll break shit and have to troubleshoot.