The firestick isn’t meant to hold kodi builds. It’s too big of a job for it but you really don’t need a build on kodi. I have two add ons with kodi and have never had a problem with anything. I use fen with real-debrid and clean it up after every use. It works perfectly. I’m not a guru or a know it all for fire sticks. I only been useing one for 5 years and never have a problem with links or buffering. It’s 100% worth it if you take care of it. Nothing plays perfectly with out managing and upkeep. But to each his own I guess. Jayhawk has a AWSOME video to help with kodi. It has helped me go from a non internet or streamer 5 years ago to programming fire sticks and niveda shields for my friends. You should watch it. Good luck. No offense either just tryn to help in a way
I don’t know why your post was referred to me but okay! 
I have the same as you but ran out of space. Adding a USB goggle doesn’t seem to help me out very much it only stores so much on it and keeps the rest in the system but when the 4K Max second gen came out I can download anything and still have room picked it up for $39 I still use a cache cleaner that helps a lot I have Kodi on a onn box as a backup when I went there last some were only giving me one stream even with realdebrid and that link didn’t work when I have time I will mess with it more but I mainly use APKs cinema, films plus, Tea Tv, and recently added Bee tv so I have more than enough I could never get to figure out how to get rid of the swish noises on Kodi I’m sure there’s a setting maybe That’s annoying and it seems more navigating to get to your show it was great some few years ago when I was introduced to it but with the APK apps They are so much easier The only problem I recently had was a show called 90 Day fiance a lot of little links when completely out for about a week and then just came back I use IPvanish with it that I got in 2019 with a Father’s Day special on Troypoint that is now $14.99 every 3 months for life I would have tried out surfshark but they responded with an email I sent them that they would match that price. As with all fire devices I still have my 2015 model firebox with game controller still working use that nightly for headphones and Wi-Fi turned off. I have it this way so I can sleep at night if any of you are having trouble sleeping turn off your Wi-Fi. I also turn off my 6.0 Dect landline cordless phone you know in Europe if you had the same phone they’re ahead of us it only works when you use the phone constantly sending signals back to the base here in the US it is constantly sending signals. My TP-Link AX 1800 has a little button on the back that you can turn off Wi-Fi that is great so the TV could still be left on with ethernet for somebody else while I’m sleeping if the signals can go through brick walls just think what it’s doing to your brain when you’re sleeping. Also check on EMFs to get an idea. Hope I’ve saved you from getting some sleeping pills. Peace out.