set interfaces ethernet eth0 address '192.168.122.14/24'
set interfaces ethernet eth0 description 'ISP1'
set interfaces ethernet eth2 address '192.168.100.150/24'
set interfaces ethernet eth0 description 'ISP2'

set policy local-route rule 10 fwmark '10'
set policy local-route rule 10 set table '10'
set policy local-route rule 20 fwmark '20'
set policy local-route rule 20 set table '20'

set protocols static route 0.0.0.0/0 next-hop 192.168.100.1
set protocols static route 0.0.0.0/0 next-hop 192.168.122.1
set protocols static table 10 route 0.0.0.0/0 next-hop 192.168.100.1
set protocols static table 20 route 0.0.0.0/0 next-hop 192.168.122.1

sudo nft add table inet mymark
sudo nft add chain inet mymark output \{type route hook output priority mangle \; policy accept\;\} 
sudo nft add rule inet mymark output ip daddr 1.1.1.1 mark set 10 comment \"Mark outgoing packets destined to host 1.1.1.1\"
sudo nft add rule inet mymark output tcp dport 443 mark set 10 comment \"Mark outgoing packets destined to port 443\"
sudo nft add rule inet mymark output tcp dport 80 mark set 20 comment \"Mark outgoing packets destined to port 80\"

vyos@r14# sudo tcpdump -ni eth2 host 1.1.1.1
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on eth2, link-type EN10MB (Ethernet), snapshot length 262144 bytes
12:50:04.735781 IP 192.168.100.150 > 1.1.1.1: ICMP echo request, id 3482, seq 1, length 64
12:50:04.774111 IP 1.1.1.1 > 192.168.100.150: ICMP echo reply, id 3482, seq 1, length 64