Degoogling communities have many posts about non-big-tech phones that run most Android apps, such as:

• The easy French Murena /e/OS (open source based on LineageOS, which is based on AOSP unfortunately) on a Dutch Fairphone or a German Shiftphone (both bootloader lockable, a security feature against persistent restart-proof OS modification by malware and pickpocket USB-hacking that these open-source alternatives rarely support)
• The secure GrapheneOS (also AOSP = Google-sabotageable future development) on a Google Pixel (the only hardware fulfilling the OS's requirements) or on the future phone promised by Motorola (both bootloader locked obviously, among many other security features)
• The seriously independent Linux phone OSs:
  -- Jolla Sailfish OS on a Jolla phone or a Sony 10 or something
  -- PostmarketOS installed to many phone options
  -- Ubuntu Touch installed to a few phone options

https://murena.com/products/smartphones/
https://doc.e.foundation/devices
( and another similar company and OS with some devices bootloader lockable:
https://shop.iode.tech/
https://iode.tech/iodeos-official-supported-devices/
)

https://grapheneos.org/faq#supported-devices

https://commerce.jolla.com/
https://buy.jolla-devices.com/product/sony-xperia-10-iii-sailfish-os/
https://docs.sailfishos.org/Support/Supported_Devices/

https://wiki.postmarketos.org/wiki/Devices

https://devices.ubuntu-touch.io/

Just keep the old Android as a spare for when Google successfully prevents something from working on the healthier alternatives, or an app requires genuine Google to work. My old Android phone stays powered off at home and I almost never need it. Any old clunker worth 20€ will do.

I use /e/OS btw - it's not very secure against hacking, but it blocks almost all big-tech surveillance. I disliked the default iPhone-style Bliss launcher, so I installed Lawnchair to make it feel like my old LG with Android.