device is on the same subnet, so no routing should be needed.
I can see ping is going out
root@Teltonika-RUTXR1:~# tcpdump -i br-lan -n -v 'icmp and net 10.0.0.0/24'
tcpdump: listening on br-lan, link-type EN10MB (Ethernet), capture size 262144 bytes
05:59:03.425043 IP (tos 0x0, ttl 64, id 55263, offset 0, flags [DF], proto ICMP (1), length 84)
10.0.0.100 > 10.0.0.2: ICMP echo request, id 15384, seq 0, length 64
default dev qmimux0 proto static scope link src x.x.x.x metric 4
10.0.0.0/24 dev br-lan proto kernel scope link src 10.0.0.100
10.45.6.0/24 dev br-lan proto static scope link metric 1
and from another device with default gateway to the RUT:
root@pve-cph-p01:~# traceroute 10.0.0.2
traceroute to 10.0.0.2 (10.0.0.2), 30 hops max, 60 byte packets
1 10.45.6.6 (10.45.6.6) 0.410 ms 0.372 ms 127.826 ms
2 10.0.0.2 (10.0.0.2) 127.816 ms 127.800 ms 127.785 ms
and ping from other device
root@pve-cph-p01:~# ping 10.0.0.2
PING 10.0.0.2 (10.0.0.2) 56(84) bytes of data.
64 bytes from 10.0.0.2: icmp_seq=1 ttl=64 time=0.401 ms
From 10.45.6.6: icmp_seq=2 Redirect Host(New nexthop: 10.0.0.2)
64 bytes from 10.0.0.2: icmp_seq=2 ttl=64 time=0.413 ms
64 bytes from 10.0.0.2: icmp_seq=3 ttl=64 time=0.352 ms
64 bytes from 10.0.0.2: icmp_seq=4 ttl=64 time=0.347 ms
64 bytes from 10.0.0.2: icmp_seq=5 ttl=64 time=0.370 ms
64 bytes from 10.0.0.2: icmp_seq=6 ttl=64 time=0.369 ms