charging is unreliable for my phone -- tried several access points including my mac

Try a different power source, a different cable, or use wireless charging (iPhone 8 or later).

Also, clean out the Lightning port on the bottom of the phone with a toothpick and a bright light to inspect it.

At the risk of stating the blindingly obvious …

… Lightning connector cable ends - being exposed when not in-use - DO tend collect to scunge.

You should see 8x shiny gold contacts on each side.

Sometimes a little “housekeeping” will solve these sorts of issues.

Check the Battery Health on your iPhone.

Home Screen > Settings > Battery > Battery Health

If the Battery Health is below 80%, it is time to replace the battery.