If anyone can help with configurations it will be helpful
The best and possible option are
connect two networks with point to point leased line and Configure static route on both sites
connect two networks with ISP can configure IPsec site -Site tunnel to smoothly exchange traffic between two sites .
3 ) connect two networks with ISP can configure ipsec- GRE tunnel .
Even natting can be done at both ends to access resource of 192.168.2.0/24 from 192.168.1.0/24
Destination natting should be configured at server hosted sites . And PAT need to be configured on 192.168.1.0/24 subnet end
So with destination natted public ip address servers resources can be access from 192.168.1.0/24 subnet network.
As Zac67 said, a tunnel suits your use case better. Here is an example with GRE on your router1:
interface tunnel0 tunnel source 188.8.131.52 tunnel destination 184.108.40.206 ip address 192.168.3.1 255.255.255.252 no shutdown ip route 192.168.2.0 255.255.255.0 tunnel 0
Remember that GRE does not provides encryption. You can use IPsec for that purpose.