Drupal 8.x

I maintain several sites that use Drupal 7 and have periodically thought "maybe I should upgrade soon".  Every time I set about to look into doing it, I find that dozens of modules are still listed as "This module is currently being ported to Drupal 8, but is not usable yet." 

I'm looking for a module to modify a field on the user record to add or delete an association to a node of content_type location.  Let's say, a user comes to greatesthardwarestore.com and he wants to find the nearest store.  He finds it with a map of geolocation fields of the 20 locations in the US.  Then...

(I know how to do everything up to this point, but this is the part I don't know.)

Hi There

I am wanting to build a website where users can sign up and list goods and services for exchange with other like minded people. I think Drupal will be a good platform to build this site on. I am new to Drupal hence I am posting here. I would appreciate guidance from more experienced drupallers on this matter. Can someone suggest to me if this site is similar to a directory listing website or not? Because if it is I can follow an online tutorial for the initial build as suggested in this link:

Hello! I can't for the life of me get rid of the message in my site-report that says "PHP APCu caching: Not Enabled. PHP APCu caching can improve your site's performance considerably. It is highly recommended to have APCu installed on your server." I have php 7.3.19-1~deb10u1, I have done "apt install php-apcu" and I've done /etc/init.d/php-fpm restart.

Checking in phpinfo() I see "apc.enabled On" and "APCu Support Enabled". Yet my Drupal 8.9.2 will not stop saying it's not installed.

I tried to make some new Menues like the Home button but when i click it, it leads to this -> URL/node/1

with the message: "The website encountered an unexpected error. Please try again later.

The recent log messages say: page not found

and x php which i guess is the problem:

Error: Call to undefined method Drupal\node\Entity\Node::URL() in creative_responsive_theme_preprocess_breadcrumb() (line 198 of /var/home/my-url/www/themes/creative_responsive_theme/creative_responsive_theme.theme)

Hello, I'm looking for user points like module for D9. Any Ideas?

Thanks